A  TREATISE 


ON 


WOODEN  TRESTLE  BRIDGES 

ACCORDING  TO  THE   PRESENT   PRACTICE 
ON   AMERICAN    RAILROADS. 


BY 

WOLCOTT    C    FOSTER. 


OP 

UHXVSESIT7 


NEW   YORK: 

JOHN    WILEY    &    SONS, 

53  EAST  TENTH  STREET. 

1891. 


COPYRIGHT,  1891, 

BY 
JOHN   WILEY  &   SONS. 


ROBERT  DBCMMOND,  FERRIS  BROS, 

Electrotype*,  Printer* 

114  &  146  Pearl  Street,  826  Pearl  Street, 
New  York.  New  York. 


PREFACE. 


IN  collecting  the  data  for  this  work,  a  circular  letter  was  sent  to  each  chief  engineer 
throughout  the  country  of  whom  the  author  could  obtain  the  address.  These  letters  met 
with  many  hearty  responses,  and  resulted  in  the  collection  of  a  very  complete  set  of  plans 
of  the  standard  trestles  in  use  on  the  different  roads. 

Tables  embodying  the  details  of  all  the  different  parts  were  compiled,  and  the  deductions 
made  from  these.  Every  effort  has  been  put  forth  to  make  the  work  as  valuable  and  com- 
plete as  possible,  without  making  it  too  bulky.  Neither  time,  pains,  nor  expense  have  been 
spared  in  its  preparation. 

As  far  as  possible  credit  has  been  given  in  the  body  of  the  work  to  the  originators  of 
any  special  design  ;  but  as  oversights  may  have  unintentionally  occurred,  a  list  of  those 
engineers  who  have  aided  the  author  is  appended. 

It  is  the  earnest  hope  of  the  author  that  the  results  of  his  labors  will  prove  worthy  of 
the  courtesy  and  aid  so  generously  extended  to  him  by  the  members  of  the  profession  at 
large,  many  of  whom  were  perfect  strangers. 

LIST   OF    THE    ENGINEERS    TO   WHOM   THE   AUTHOR   IS   INDEBTED    FOR    AID    IN    PREPARING 

THIS   WORK. 


Alger,  Chas.  E. 
Ansart,  Felix. 
Bates,  Onward. 
Becker,  M.  J. 
Berg,  Walter  G. 
Bissel,  F.  E. 
Blunt,  Jno.  E. 
Boiton,  C.  M. 
Booker,  B.  F. 
Bovven,  A.  L. 
Briggs,  R.  E. 
Buxton,  C. 
Canfield,  E. 
De  Caradene,  A. 
Curtis,  F.  S. 
Davery,  R.  A. 
Dick,  H.  B. 
Dorsey,  W.  H.,  Jr. 
Elliott,  R.  H. 
Fisher,  J.  B. 


Fitch,  A.  B. 
Fratt,  F.  W. 
Gore,  Th. 
Greenleaf,  J.  L. 
Griggs,  J. 
Hawks,  J.  D. 
Howe,  W.  B.  W.,  Jr. 
Hoyt,  Wm.  E. 
Kennedy,  H.  A. 
Kriegshaber,  V.  H. 
Levings,  Chas. 
Lum,  D.  W. 
Martin,  M.  A. 
McVean,  J.  J. 
Miller,  N.  D. 
Mills,  A.  L. 
Molesworth,  A.  N. 
Monroe,  J.  A. 
Montfort,  R. 
Morton,  T.  L. 


Nelson,  J.  P. 
Nettleton,  G.  A. 
Nicholson,  G.  B. 
Patton,  E.  B. 
Perris,  Fred.  T. 
Reed,  A.  L. 
Rich,  W.  W. 
Riffle,  F. 
Rowe,  S.  M. 
Sage,  I.  Y. 
Schenck,  A.  A. 
Smith,  P.  A. 
Spofford,  Parker. 
Swift,  A.  J. 
Weeks,  I.  S.  P. 
Wheeler,  D.  M. 
White,  H.  F. 
Whittemore,  D.  J. 
Woods,  J.  E. 
Zook   F.  K. 


CONTENTS. 


PART 


PAGE 

PREFACE,      ...  .     ni 

TECHNICAL  TERMS  AND  NAMES,        .  •     ix 

CHAPTER   I. 

INTRODUCTION. 

Extent Necessity  for  wooden  trestles — Inspection — Repair — Economy — Designing — Keraning  devices 

— Fires  and  fire  protection — Classification,     .....  .1 

CHAPTER    II. 

PILE-BENTS. 

When  used— Timber— Qualities— Arrangement  of  piles— Lengthening  of  piles— Shoeing  piles— Split- 
ting of  piles — Driving — Construction  records — Cost— Fastening  to  cap,  .  .  .6 

HAPTER    III. 

PILE-DRIVERS. 

Mounted  pile-drivers — Steam  pile-drivers — Floating  pile-drivers — Track  pile-drivers — Steam  hammers,  .     13 

CHAPTER  IV. 

FRAMED     BENTS. 

Foundations — Sills — Posts — Caps — Joints — Spacing, 24 

CHAPTER   V. 

FLOOR    SYSTEM. 

Corbels — Stringers — Ties — Guard-rails — Fastening  down  floor  system, 31 

CHAPTER  VI. 

BRACING,    COMPOUND-TIMBER    TRESTLES,    HIGH    TRESTLES,   TRESTLES    ON    CURVES,   AND 

MISCELLANEOUS    TRESTLES. 

Sway-bracing — Counter-posts — Longitudinal  bracing — Lateral  bracing — Compound-timber  trestles — 
High  trestles — Classification  and  description — Longitudinal  bracing — Lateral  bracing — Trestles  on 
curves — Elevating  the  rail — Double-track  trestles— Knee-braced  trestles — Round  timber  trestles — 
Trestles  with  solid  floors, 39 

CHAPTER   VII. 

IRON    DETAILS. 

Cut  spikes  —  Boat-spikes  —  Drift-bolts  —  Dowels  --  Bolts— Lag- screws  —  Separators— Cast  washers- 
Wrought  washers— Nut-locks -45 

v 


vi  CONTENTS. 

CHAPTER  VIII. 

CONNECTION    WITH   THE    KMHAXKMKNT    AND    PROTECTION    AGAINST   ACCIDENTS. 

Bank-sills — Bank-bent — Rerailing-guard — Refuge-bays — Foot-walks — Water-tubs — Iron-covered  strin- 
gers—  Earth-covered  floors 52 

CHAPTER   IX. 

FIELD-ENGINEERING   AND    ERECTION. 

Laying  out  in  the  field — Erecting — Tools  employed  in  building 56 

CHAPTER   X. 

PRESERVATION   AND   STANDARD   SPECIFICATIONS. 

Preservation  of  joints — Standard  specifications — Form  of  proposal, 61 

CHAPTER   XI. 

BILLS  OF   MATERIAL,   RECORDS   AND   MAINTENANCE. 

Bill  of  timber— Bill  of  iron— Aids  to  making  out  estimates— Feet  B.  M.— General  bill  of  timber— Con- 
struction records— Masonry— Timber  estimate— Division  trestle  estimate— Inspection— Track- 
walkers' report— Inspection  records— Bridge  instructions  of  the  N.  Y.,  L.  E.  &  W.  R.  R.  and  the 
B.,  C.  R.  &  N.  R.  R.— Premiums  for  repair— Repairs— Tests— Bridge  numbers,  .  .  .  .70 


PART   II. 


SECTION   I. 

PILE-TRESTLES. 

Plate  I.  Denver  &  Rio  Grande  Railroad 86,  87 

II.  Toledo,  St.  Louis  &  Kansas  City  Railroad 88,89 

III.  Atlantic  &  Pacific  Railroad 9°- 91 

IV.  Chicago  &  West  Michigan  Railway, 92,  93 

V.  Minneapolis  &  St.  Louis  Railway, •  94.  95 

VI.  Chicago  &  Northwestern  Railway, 96,  97 

_X:|'  I  Louisville  &  Nashville  Railroad,  98>  99 

IX.  Boston  &  Albany  Railroad, 100,  101 

SECTION    II. 

FRAMED   TRESTLES. 

Plate  X.  Chicago  &  West  Michigan  Railway, 102,  103 

XI.  Pennsylvania  Railroad 104,  105 

XII   ) 
Ji:     \  San  Francisco  &  North  Pacific  Railroad, 106,107 

II 1 1.  ' 

XIV.  \ 

XV.  V  Norfolk  &  Western  Railroad, io8toiii 

XVI.  ? 

XVII.  Louisville  &  Nashville  Railroad, 112,113 

XVIII.  Oregon  Pacific  Railroad, 114,115 


CONTENTS. 


vn 


XIX.  Ohio  Connecting  Railway,            .  , 

XXI   [  Charleston,  Cincinnati  &  Chicago  Railroad, 1 1810121 

XXII.  Minneapolis  &  St.  Louis  Railway I22   J2 

XXIII.  Georgia  Pacific  Railway ' 

XXIV.  Oregon  &  Washington  Territory  Railroad ,    126*  12- 

XXV.  Fort  Worth  &  Denver  City  Railway,           ....  '    128    i2/ 

XXVI.  Richmond  &  Danville  Railroad, 
XXVII.  Cleveland  &  Canton  Railroad,     . 
XXVIII   I 
XXIXJ  California  Central  Railway,        .  13410136 

XXX.  Toledo,  St.  Louis  &  Kansas  City  Railroad,         ...  r?7 

XXXI.  Atlantic  &  Pacific  Railroad,        ....*.'.  138130 

XXXII.  Milwaukee  &  Northern  Railroad, 
XXXIII.  )  ., 
XXXIV •  f  Minneapolis  &  Manitoba  Railroad 14210145 

XXXV.  New  York,  Woodhaven  &  Rockaway  Railroad, I46   I47 

XXXVI.  New  York,  Providence  &  Boston  Railroad, 

XXXVII.  Intercolonial  Railway ieoto  IM 

XXXVIII.  Esquimalt  &  Nanaimo  Railway,          . 

INDEX,  .  'm  '    ^ 


TECHNICAL   TERMS  AND  NAMES. 


THE  following  list  gives  the  names  and  their  synonyms  of  some  of  the  more  important 
parts  of  wooden  trestles.  In  connection  with  this  list  see  Figs,  i  and  2,  to  which  the  num- 
bers opposite  the  names  refer. 


FIG.  i. 


FIG.  2. 


Bent,  Framed,  20.     (See  page  24.) 

Pile,  19.  "        "      6 

Cluster.  "         "     41 

Bent  Brace,  see  Sway-brace. 
Block,  see  Sub-sill. 
Bolster,  see  Corbel. 
Cap,  3.     (See  page  12.) 
Chord,  see  Stringer. 
Corbel,  Bolster.     (See  page  31.) 
Cross-tie,  2.  "       "      35 

Cut-off,  17.  "      ii 

Dapping,  see  Notching. 
Fender,  Guard-rail,  i.     (See  page  35.) 
Gaining,  see  Notching. 
Girt,  see  Longitudinal  Brace. 
Girder,  see  Stringer. 

Guard-rail,  Fender,  Ribbands,  i.     (See  page  35.) 
Jack-stringer,  see  Stringer. 

Longitudinal  Brace,  Girt,  Wai  ing-strip,  22.     (See 
Mortise,  13.  [page.  39) 

Mud-sill,  see  Sub-sill. 
Notching,  Gaining,  Dapping,  18.     (See  page  30.) 


Outside  Stringer,  see  Stringer. 

Packing-block,  Packing  piece,  5.     (See  page  32.) 

Packing-bolt,  7.  "      "       48 

Packing-piece,  see  Packing-block. 

Packing-washers,  see  Separator. 

Piles,  Batter,  Inclined  Brace,  16.     (See  page  7.) 

Vertical,  Plumb,  Upright,  9.      "       "     7 
Posts,  Batter,  Inclined,  12.  "       "    28 

Vertical,  Plumb,  Upright,  10     "       "    28 
Ribbands,  see  Guard-rail.  [pages  32  and  50.) 

Separator,  Packing-washer,  Thimble  Spool,  6.    (See 
Sill,  14.     (See  page  27.) 
Spool,  see  Separator. 
Stringer,  Chord,  Girder. 

Track,  3.  (See  page  32.) 

Outside,  Jack,  4.  "       "     34 
Sub-sill,  Mud-sill,  Blocks,  15.      (See  page  2^.) 
.Sway-brace,  Bent  Brace,  21.  " 

Tenon,  11.  " 

Thimble,  see  Separator. 
Track-stringer,  see  Stringer. 
Waling-strip,  see  Longitudinal  Brace. 

jx 


39 

12 


ABBREVIATIONS. 


A.  &  P.  R.  R. ;  Atlantic  &  Pacific  Railroad. 

B.,  C.  R.  &  N.  R.  R.;  Burlington,  Cedar  Rapids  &  Northern  Railroad. 

B.  &  M.  R.  R.  R.  in  Neb. ;  Burlington  &  Missouri  River  Railroad  in  Nebraska. 

C.  &  A.  Ry. ;  Chicago  &  Atlantic  Railway. 

C.,  B.  &  Q.  R.  R.  ;  Chicago,  Burlington. &  Quincy  Railroad. 

C.,  C.  &  C.  R.  R. ;  Charleston,  Cincinnati  &  Chicago  Railroad. 

C.,  M.  &  St.  P.  Ry. ;  Chicago,  Milwaukee  &  St.  Paul  Railway. 

C.,  N.  O.  &  T.  P.  Ry. ;  Cincinnati,  New  Orleans  &  Texas  Pacific  Railway. 

C.  &  S.  Ry.  ;  Charleston  &  Savannah  Railway. 

C.  &  W.  M.  Ry.  ;  Chicago  &  West  Michigan  Railway. 

D.,  T.  &  Ft.  W.  R.  R. ;  Denver,  Texas  &  Fort  Worth  Railroad. 

G.,  C.  &  S.  F.  R  R. ;  Gulf,  Colorado  &  Santa  Fe  Railroad. 

K.  C.,  Ft.  S.  &  M.  R.  R.  ;  Kansas  City,  Fort  Scott  &  Memphis  Railroad. 

K.,  G.  B.  &  W.  R.  R. ;  Kewaunee,  Green  Bay  &  Western  Railroad. 

L.  &  N.  R.  R.  ;  Louisville  &  Nashville  Railroad. 

M.,  K.  &  T.  Ry.  ;  Missouri,  Kansas  &  Texas  Railway. 

N.  Y.,  P.  &  B.  R.  R.  ;  New  York,  Providence  &  Boston  Railroad. 

N.  Y.,  W.  S.  &  B.  R.  R. ;  New  York,  West  Shore  &  Buffalo  Railroad. 

R.  &  D.  R.  R. ;  Richmond  &  Danville  Railroad. 

St.  P.,  M.  &  M.  R.  R. ;  St.  Paul,  Minneapolis  &  Manitoba  Railroad. 

S.  F.  &  N.  P.  R.  R. ;  San  Francisco  &  North  Pacific  Railroad. 

S.,  F.  &  W.  Ry. ;  Savannah,  Florida  &  Western  Railway. 

T.,  St.  L.  &  K.  C.  R.  R. ;  Toledo,  St.  Louis  &  Kansas  City  Railroad. 


UHI7ERSIT7 
C 


A   TREATISE    ON    WOODEN    TRESTLE    BRIDGES. 


I. 


CHAPTER  I. 
INTRODUCTION. 

THE.  amount  of  Wooden  Trestling  in  this  country  is  very  large,  but  few  probably  realiz- 
ing its  extent  unless  they  have  thoroughly  studied  the  subject.  At  the  present  time  there 
are  about  2400  miles  of  single-track  railway-trestle  in  the  United  States,*  of  which  we  can  con- 
sider about  one  quarter  as  only  temporary,  to  be  replaced  by  embankment.  "  Of  the  remain- 
ing 1800  miles,  at  least  800  miles  will  be  maintained  in  wood."  This  2400  miles  is  composed 
of  about  150,000  separate  structures  having  about  730,000  spans  or  more.  Table  I  gives  the 
general  data  as  to  the  amount  of  bridges  and  trestles,  and  the  average  rate  per  mile  of  track 
on  some  of  the  more  important  systems. 

TABLE  I. 

Amount  of  Bridging  and  Trestling  in  Different  Parts  of  the  United  States,  and  the  Rate  per  Mile  of  Track. 

(COOPER'S  TABLE  No.  3.) 


System  of  Railroad  or  State. 

Miles  of  Road. 

Total  Length  of 
Bridges  and  Trestles 
in  feet. 

Lin.  ft.  of  Bridges 
and    Trestles    per 
Mile  of  Road. 

New  York  Central  and  West  Shore  Railroads, 
New  York,  Lake  Erie  &  Western  Railroad,    . 

2,894 
I.5H 

T,   q86 

364,722 
95,509 

AAt  QOO 

126 

63 
1  1O 

Roads  in  Pennsylvania,    ....                           . 
"       "  New  England,  ....                 . 
Wabash  System,        . 
Missouri  Pacific  System,           ...                 . 
Chicago,  Milwaukee  &  St.  Paul  Railroad, 
St.  Louis  &  San  Francisco  Railway, 
Denver  &  Rio  Grande  Railroad,      .                           .         . 
Union  Pacific  Railroad  . 

4-352 
2,199 
1,636 
4,707 
5,727 
1,441 
1,458 

4-754 

2  ACK 

336.957 
176,700 
I6O,O25 

566,953 
614,736 
130,075 
IO2,I95 
276,032 
•522  67Q 

77 
80 
98 

120 
107 
90 
70 

58 

121 

Queen  and  Crescent  System,  .         .         . 
Roads  in  Illinois,       .....                          . 
"      "  Michigan,           ....                 . 
"      "  Iowa,          .        .         .        .         .        .        . 

I-I39 

8,539 
4.151 

7  778 

299,222 
707,535 
249-345 
I  O49   386 

231  t 

*<? 
60 

ns 

Central  Railroad  and  Banking  Co.  of  Georgia, 

1,487 

'73-975 

117 

Totals,           

cn,8;7 

6,071,946 

IOI 

*In  the  first  part  of  this  chapter  a  considerable  portion  of  the  matter  relating  to  statistics  was  taken 
from  a  paper  by  Theodore  Cooper  on  American  Railroad  Bridges,  Trans.  Amer.  Soc.  C.  E.,  July  1889. 

S.  C.  Clark  in  Scribner's  Magazine  for  June  1888  gives  the  length  of  wooden  trestling  in  the  United 
States  at  about  2127  miles. 

t  Includes  the  crossing  of  Lake  Pontchartrain,  a  trestle  22  miles  long. 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


"  It  shows  that  the  relative  amount  of  bridges  and  trestles  varies  in  different  localities 
from  58  feet  per  mile  to  231  feet  per  mile.  This  last,  however,  is  excessive  from  including 
the  crossing  of  Lake  Pontchartrain,  near  New  Orleans,  on  a  trestle  22  miles  long.  Omitting 
this,  we  would  get  only  162  feet  per  mile  as  the  maximum." 

"  These  variations  are  not  entirely  due  to  geographical  location,  as  might  appear  at 
first  thought.  They  are  also  affected  by  principles  governing  the  original  location  of  each 
road  or  division  of  a  system.  The  alignment  and  grade  may  have  been  sacrificed  to  the 
avoidance  of  bridges  and  trestles,  or  the  contrary." 

"  From  the  large  mileage  covered  by  our  table,  we  can  rely  with  considerable  confidence 
upon  our  average.  Taking,  therefore,  100  feet  per  mile  as  our  basis  of  estimate,  we  have  for 
the  160,000  miles  of  railroad  in  the  United  States,  16,000,000  feet  or  3030  miles  of  bridges 
and  trestles.  Table  II  gives  the  distribution  of  the  bridges  upon  26,000  miles  of  railroad  into 
spans  of  different  length." 

TABLE  II. 

Distribution  of  Bridges  and  Trestles  in  Spans  of  Different  Lengths,  in  Totals  of  Lineal  Feet. 

(COOPER'S  TABLE  No.  4.) 


Miles  of 
Road. 

Trestles  and 
Spans  under  20 
feet. 

Spans  20 
to  50  feet. 

Spans  50 
to  100  feet. 

Spans  TOO  to 
150  feet. 

Spans    150 
to  200  feet. 

Spans   200 
to  300  feet. 

Spans 
300  to  400 
feet. 

Spans 
400  to  500 
feet. 

Spans 
over  500 
feet. 

Total. 

Average 
per    Mile 
of  Road. 

26,288 

2,299,758 

85,181 

94-165 

149,121 

80,551 

29,542 

5.677 

1,211 

1,040 

2,746,246 

104.7 

"  Using  this  as  a  basis  of  estimate,  the  3030  miles  of  trestles  and  bridges  in  the  United 
States  should  be  distributed  as  follows : 

Trestles  and  Spans  under  20  feet, 
Spans  20  to  50  feet,  . 

"      50  to  100  " 

"      100  to  1 50  feet, 

"      150  to  200    " 

"      over  200  feet 


Miles.                  No  of  Spans. 
2,424                     727,200 
121                         18,150 
130                          9.IOO 
100                          8,000 
109                          3,300 
56                           1,150 

3.030 


766,900 


The  above  includes  all  bridges  of  either  wood  or  iron." 

In  order  that  we  may  more  fully  comprehend  the  meaning  of  these  figures,  let  us  find 
the  money  value.  Taking  the  amount  of  trestling  at  an  even  2400  miles  =  12,672,000 
lineal  feet.  Now  about  $6  per  lineal  foot  is  a  fair  average  for  the  cost,  with  timber  at 
$30  per  M,  B.  M.,  erected.  At  this  rate  the  trestling  represents  an  expenditure  of 
$76,032,000.  With  an  average  life  of  eight  years,  which  is  perhaps  a  little  too  long  taking 
everything  into  consideration,  the  annual  expenditure  for  repairs  and  renewals  alone 
amount  to  $9,504.000,  necessitating  the  use  of  316,800,000  feet  (B.  M.)  of  timber.  Capitaliz- 
ing this  annual  expenditure  at  4  per  cent,  we  find  it  represents  $237,600,000.  Now,  if,  as 
Cooper  estimates,  two  thirds  of  the  total  amount  of  trestling  is  capable  of  being  replaced,  we 
will  be  justified  in  spending  $168,400,000,  with  interest  at  4  per  cent,  in  accomplishing  this 
end.  As  one  third,  or  800  miles,  will,  of  necessity,  remain  as  it  is,  there  will  be  a  continual 
annual  expenditure  of  $3,168,000  for  repairs  and  renewals,  requiring  105,600,000  feet  (B.  M.) 
of  timber,  and  representing  a  capitalized  value  of  $79,200,000  at  4  per  cent.  These  figures 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


do  not  take  into  account  any  increase  in  the  mileage  from  the  building  of  new  roads.  From 
the  above  we  can  see  what  an  enormous  annual  drain  there  is  upon  our  forests  merely  for  the 
maintenance  of  what  has  been  considered  one  of  the  smaller  and  less  important  of  railway 
properties,  and  these  figures,  large  as  they  are,  are  rather  too  low  than  otherwise. 

Converting  these  capitalized  values  into  earthwork,  we  find  that  we  could  build  the  fol- 
lowing number  of  miles  of  embankment,  twenty  feet  high,  complete,  ready  for  the  rails 

TABLE  II  (a). 

Amount  of  Embankment,  20  Feet  high,  which  can  be  built  for  the  Capitalized  Value  of  the  Annual  cost  of 

Repairs  for  the  1600  miles  of  Replaceable  Trestle. 

Ties 2640  per  mile,  @  45  cents  each. 

Ballast, 2738  cubic  yards  per  mile,  @  50  cents  per  cubic  yard. 


Cost  of  earth  per  cubic  yard,      

16  c. 

i8c. 

20  c. 

22  C. 

5,262 

4,722 

4,283 

3,0l8 

But  of  this  replaceable  two  thirds  or  1600  miles,  only  about  600  miles  is  capable  of  being 
replaced  by  embankment.  Now  taking  the  cost  of  replacing  this  600  miles  in,  say,  2O-foot 
earth  embankment,  we  would  have  the  amount  left  as  indicated  in  Table  III.  for  replacing 
the  remaining  1000  miles  with  other  permanent  structures. 

TABLE  III. 

Showing  Cost  of  600  Miles  of  2O-foot  Embankment  Complete,  and  Balances. 


$158,400,000. 

Cost  of  earth  per  cubic  yard,      

16  c. 

i8c. 

20  C. 

22  C. 

Cost  of  600  miles  of  road  complete   except 

$18,058,800 

$20,124,000 

$22,189,800 

$24,255,600 

Balance,  applicable  to  replacing  1000  miles  of 
trestles  by  other  structures  such  as  iron  or 
masonry  bridges,  etc  

$140,341,200 

$138,276,000 

$136,210,200 

$134,144,400 

NOTE. — In  this  table  the  same  data  have  been  used  as  in  Table  II.  (a),  viz.: 


Cost  of  earth  per  cubic  yard,     

16  c. 

18  c. 

20  c. 

22  C. 

$i  188 

$i  188 

$i  188 

$1,188 

Ballast   I'x  14',  per  mile    

i  760 

i  ifio 

i  ^60 

i  ^60 

Embankment,  14'  x  20',  (172,  128  cubic  yards),  per  mile, 

27.541 

30.983 

34.426 

37.869 

$30,098 

$^'?,;4.o 

$^6,08^ 

&4.O.A26 

There  are  many  other  reasons,  in    addition  to  the  above,  which  would  justify  a  much 
larger  expenditure  than  this  to  secure  the  replacement  of  the  trestles. 

Notwithstanding   the  great  importance  of  the  subject,  and  the  fact  that  a  large  part  of 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


the  expense  of  building  many  new  roads  is  chargeable  to  these  structures,  no  effort  of  any 
moment  has  been  made  to  collect  and  publish  together  any  considerable  amount  of  data  relat- 
ing to  it ;  the  most  extensive  and  important  paper  so  far  published  on  trestling  probably 
being  that  by  Prof.  Jameson  in  TJic  Engineering  and  Railroad  Journal  for  the  latter  part 
of  1889  and  early  part  of  1890. 

A  good  wooden  structure  is  preferable  to  the  cheap  iron  ones  that  some  roads  seem 
determined  to  erect.  They  have  proven  the  salvation  of  many  a  new  enterprise,  when,  had 
it  been  absolutely  necessary  to  resort  to  the  use  of  stone  or  iron,  or  to  make  enormous 
fills,  the  project  must  have  been  abandoned  on  account  of  the  lack  of  capital  wherewith  to 
erect  these  costly  works.  Wooden  trestles  for  the  most  part  are,  of  course,  built  with  the  idea 
of  their  being  only  temporary  expedients,  to  be  replaced  in  time,  as  rapidly  as  the  finances 
of  the  company  may  permit,  by  something  more  permanent.  However,  a  well-built  trestle 
of  good  material  will  last  a  long  time,  depending  to  a  certain  extent  on  climatic  conditions. 
If  properly  designed  and  cared  for  they  form  an  efficient  portion  of  the  roadway.  They 
require  constant  watching;  and  the  moment  any  sign  of  weakness  or  injurious  amount  of 
decay  appears  it  should  be  remedied  immediately.  The  inspection  should  be  regular  and 
frequent,  and  placed  in  careful,  trustworthy,  and  competent  hands.  It  is  the  practice  on 
some  roads,  and  a  very  pernicious  one  which  cannot  be  too  strongly  condemned,  to  allow 
these  structures  to  deteriorate  until  they  are  just  about  ready  to  fall  every  time  a  train  passes 
over  them,  before  the  management  will  attempt  to  make  any  repairs,  thinking  perhaps  that 
they  are  accomplishing  wonders  in  the  way  of  economy.  In  consequence  of  this  way  of 
conducting  affairs  there  is  scarcely  a  week  that  passes  but  we  read  of  one  or  more  trestle 
accidents. 

The  height  at  which  it  becomes  more  economical  to  replace  embankment  by  trestling 
varies  in  different  locations,  depending  upon  the  cost  of  lumber,  labor,  and  the  facilities  for 
obtaining,  and  the  nature  of,  the  material  wherewith  to  make  the  fill  (see  Table  IV).  There 
are  many  places  where  an  embankment  would  be  altogether  out  of  the  question,  such  as 
across  water-ways,  swamps  with  deep,  soft  mud,  etc.;  and  the  only  resort  then  is  either  to 
wooden  or  iron  structures. 

TABLE  IV. 

Showing  Approximate  Relative  Cost  of  Embankment  and  Trestle  in  sections  of  100  feet,  excluding  Rails, 
Ties,  and  Ballast  on  former,  and  Rails,  Guard-rails,  and  Ties  on  latter. 


TKKSTI.K. 

Height  from 
Surface  of 
Ground  to 
Grade 
(Sub-grade) 

Embankment  per  Cubic  Yard  in  Cents.    Road- 
bed 14  feet  wide,  Slope  ij£  to  i. 

Timber  erected  (including  iron)  per  M.,  B.  M. 

Pile-trestle—piling  35  c.  per  lin.  ft. 
in  place;  average  penetration  10  ft. 

Framed  Trestles. 

16 

18 

20 

22 

$3° 

$35 

$40 

$3° 

$35 

$40 

5 

$64 

$72 

$80 

$88 

$376 

$407 

$439 

$283 

$33° 

$378 

10 

"3 

127 

141 

155 

441 

476 

512 

385 

449 

5H 

15 

325 

366 

406 

447 

508 

544 

580 

464 

541 

618 

20 

521 

587 

652 

718 

576 

6.3 

651 

541 

631 

721 

25 

764 

859 

955 

1050 

748 

803 

858 

796 

928 

1060 

30 

1049 

1180 

1312 

1443 

816 

872 

928 

872 

1017 

1163 

35 

1380 

1552 

1725 

1897 

990 

1065 

1  140 

1058 

1234 

1410 

40 

1754 

1974 

2193 

2412 

1057 

1132 

1218 

"33 

1322 

1510 

45 

2174 

2446 

2717 

2989 

1  202 

1404 

1606 

A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


If  it  is  necessary  to  place  a  masonry  structure  through  a  portion  of  the  embankment, 
then  the  height  at  which  it  will  be  more  economical  to  build  a  trestle  will  be  considerably 
lowered. 

While  the  cost  of  an  embankment  increases  in  a  vastly  greater  ratio  than  its  height,  the 
cost  of  trestling  does  not  increase  nearly  as  rapidly  as  its  height,  especially  when  under  fifty 
feet.  This  fact  is  very  clearly  shown  in  Table  V. 

TABLE  V. 

Cost  of  Pile  and  Framed  Trestles  complete,  including  Floor  Systems,  for  Different  Heights, 

in  Sections  of  100  feet. 


Pile. 

Framed. 

Height. 

$30 

$35 

$40 

830 

$35 

$4o 

5 

$546 

$605 

$665 

$453 

$528 

$604 

IO 

611 

674 

738 

555 

647 

740 

15 

678 

742 

806 

634 

739 

844 

20 

746 

811 

877 

711 

829 

947 

25 

918 

IOOI 

1084 

966 

1126 

1286 

3° 

986 

1070 

1154 

1042 

1215 

1389 

35 

1160 

1263 

1366 

1228 

1432 

1636 

40 

1227 

1332 

1444 

1303 

1520 

1736 

45 

1372 

1602 

1832 

A  few  engineers  have  advocated  the  use  of  mathematics  in  the  designing  of  trestles,  but 
as  wood  is  an  article  whose  strength  and  properties  vary  rather  widely  with  every  piece,  no 
dependence  whatever  can  be  placed  on  the  results,  and  such  practice  is  to  be  condemned. 
It  is  far  wiser  to  merely  follow  one's  judgment  and  the  results  of  the  experience  of  others  as 
to  the  proper  proportioning  of  the  various  parts,  gained  from  experience  in  dealing  with  the 
wood,  than  to  follow  any  special  set  of  mathematical  formulas. 

It  will  probably  be  impossible  to  ever  thoroughly  standardize  the  plan  of  trestle  design, 
as  there  are  about  as  many  styles  as  designers.  There  also  appears  to  be  a  tendency  to  draw 
up  the  specifications  relating  to  this  subject  in  a  loose  and  slipshod  manner.  This  is  to  be 
much  regretted  ;  as  great  care  and  attention  in  proportion  to  the  importance  of  the  subject 
should  be  devoted  to  this  part  of  the  railway's  property  as  to  any  other. 

All  structures  of  this  kind,  especially  those  of  any  extent  whatever,  should  be  protected 
by  a  re-railing  device  of  some  kind,  though  there  are  still  few  that  are  so  protected.  Not 
only  should  this  be  the  case,  but  they  should  also  have  some  kind  of  fire  protection  and 
convenient  means  for  the  extinguishment  of  fires. 

There  may  be  said  to  be  two  general  classes  of  wooden  trestle  bridges,  namely,  those  in 
which  the  bents  consist  exclusively  of  piles  and  a  cap  and  hence  are  known  as  PlLE- 
TRESTLES,  and  those  in  which  the  timbers  composing  the  bents  are  squared,  and  framed 
together,  and  known  as  FRAMED  TRESTLES.  Pile-trestles  are  seldom  used  for  heights  above 
thirty  feet,  and  it  is  only  occasionally  that  they  are  built  as  high  as  this.  Framed  trestles  may 
be  of  almost  any  height,  though  requiring  special  designs  for  those  above  thirty  to  forty  feet. 
For  trestles  above  forty  feet  high  the  cluster-bent  form  seems  to  be  quite  a  favorite  class  of 
design. 


CHAPTER  II. 
PILE-BENTS. 

PlLE-BENTS  are  generally  used  where  the  ground  is  quite  soft,  and  may  either  occasionally 
or  constantly  be  covered  with  water ;  also  where  the  distance  from  the  rails  to  the  surface  of 
the  ground  is  not  very  great.  There  is  one  grave  objection  to  high  pile-trestles,  and  that  is 
that  the  top  end  of  the  tree,  and  hence  the  poorest  timber,  is  in  the  ground,  and  is  liable  to 
very  rapid  destruction  by  the  elements  at  the  ground-line.  In  order  to  retard  this  decay  as 
much  as  possible,  it  is  recommended  in  the  Report  of  the  Ohio  Railway  Commissioners  for 
1884  that  the  piles  be  painted  for  a  short  distance  above  and  below  the  ground-line  with  hot 
tar.  It  has  also  been  said  that  a  coat  of  whitewash  is  beneficial  where  there  is  no  water  other 
than  rain  to  wash  it  off. 

The  timber  used  for  piles  varies  with  the  location,  depending  very  largely  upon  the  kind 
growing  in  the  surrounding  country.  Among  the  varieties  employed  are  the  following,  to  be 
preferred  in  the  order  named,  the  first  being  the  most  durable : 

Red  Cedar.  White  Pine.  Post  Oak. 

Red  Cypress.  Redwood.  Red  Oak. 

Pitch  Pine.  Elm.  Black  Oak. 

Yellow  Pine  (close-  Spruce.  Hemlock, 

grained,  long  leaf).  White  Oak.  Tamarac. 

Order  not  known : 

Red  Ash.  Chestnut.  Buttonwood. 

White  Ash.  Beech.  Red  or  Norway  Pine. 

White  Cedar.  Scrub  Oak. 

They  should  be  of  straight,  sound,  live  heart  timber,  perfectly  free  from  windshakes, 
wanes  ;  large,  loose,  black,  or  decayed  knots  ;  cracks,  worm-holes,  and  all  descriptions  of  decay  ; 
and  should  be  stripped  of  bark.  Some  engineers  prefer  the  piles  to  be  hewed  or  sawed 
square.  If  piles  are  squared,  they  should  be  hewed  rather  than  sawed,  and  be  as  free  as 
possible  from  axe-marks.  Squared  piles  ought  to  be  at  least  12  inches  across  each  face,  and 
not  show  more  than  2  inches  of  sap  at  the  corners. 

Round  piles  are,  as  a  rule,  from  12  inches  to  15  inches  across  the  butt  after  being  cut  off, 
and  when  they  are  wider  than  the  cap,  the  portion  which  projects  on  either  side  should  be 
adzed  off  to  an  angle  of  at  least  45°  (Fig.  7). 

The  arrangement  of  the  piling  varies  considerably,  almost  every  constructor  having  his 
own  plan  and  ideas.  The  nature  and  amount  of  the  traffic  should  be  carefully  considered. 
For  bents  up  to  five  feet  in  height,  where  the  traffic  is  not  very  heavy,  but  th  ree  piles  driven 
vertically  are  required.  One  should  be  placed  on  the  centre-line,  and  one  on  either  side  from 
3  feet  6  inches  to  5  feet  out  (Fig.  3). 

6 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


When  the  bents  are  from  5  feet  to  10  feet  high,  and  on  lower  ones  on  trunk  lines,  or 
where  the  traffic  is  heavy,  four  piles  driven  vertically  should  be  used.  The  inner  ones  may 
be  spaced  from  4  feet  to  5  feet  between  centres,  and  the  outer  ones  about  1 1  feet  from  centre 
to  centre  (Fig.  4).  If  the  piles  can  be  driven  into  the  ground  for  a  depth  of  8  feet  or  10 
feet,  and  have  a  good  bearing,  it  will  not  in  general  be  necessary  to  use  sway-bracing. 


.,?  I 


SCALE  OF  FEET 


FIGS.  3  TO  7. — PILE-BENTS. 


Above  10  feet  in  height  it  is  well  to  drive  the  outside  piles  at  a  batter.  According  to 
present  practice,  this  varies  from  I  inch  to  3  inches  per  foot.  From  2\  to  3  inches  is  to  be 
preferred,  as  it  gives  a  broader  base  and  greater  stiffness  to  the  structure  (Fig.  5).  The 
outer  piles  then  perform  to  a  certain  extent  the  function  of  sway-braces  and  guys  as  well  as 
supports.  Bents  between  10  feet  and  20  feet  high  should  be  braced  with  one  set  of 
sway-braces,  while  above  this  it  is  advisable  to  divide  the  bent  into  two  stories,  so  far  as  the 
bracing  goes,  making  use  of  two  X's,  with  two  horizontal  sticks  between  them.  It  is  fre- 
quently well  also  to  use  longitudinal  girts.  But  this  subject  of  bracing  will  be  thoroughly  dis- 
cussed in  a  succeeding  chapter. 

Instead  of  driving  the  outside  piles  at  their  full  batter,  the  Burlington  &  Missouri  River 
R.  R.  in  Nebraska*  drive  them  with  a  batter  of  I  inch  per  foot,  and  then  spring  the  top  ends 
to  place  (Fig.  6).  The  following  table  gives  the  spacing: 

TABLE  VI. 

Spacing  of  Piles,  Burlington  &  Missouri  River  R.   R.  in  Nebraska. 


Height  of  Bent. 

Inside  Piles  (vertical). 

Outside  Piles.    Driven  batter  i  in.  per  ft. 

c  —  c. 

Distance  either  side 
centre-line. 

c  —  c  at  ground. 

Distance  either  side 
of  centre-line. 

Up  to  10  feet,      
10  to  1  6  feet,        ...... 

5ft. 
5  " 
5  " 

2  ft.  6  in. 
2    "    6    " 
2   "    6   " 

1  I  ft.  f 
15    " 
17    " 

5  ft.  6  in. 

7  ••   6  » 
8  •«   6  " 

l6  tO  22      "               

All  at  top  immediately  beneath  cap,  . 

5  ft. 

2  ft.  6  in. 

II  ft. 

5  ft.  6  in. 

*  I.  S.  P.  Weeks,  Chief  Engineer  C.,  B.  &  Q.  R.  R.,  west  of  the  Missouri  River, 
t  Outside  piles  vertical. 


8  A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 

Where  soft  ground  extends  to  a  great  depth  two  or  more  piles  may  be  fastened  together 
end  to  end,  if  necessary  The  first  pile  is  driven  until  the  top  is  nearly  to  the  surface  of 
the  ground  or  water,  when  it  is  cut  off,  trimmed  up,  and  the  second  pile  stood  upon  and 
fastened  to  it.  The  driving  is  then  continued  as  before,  and  more  piles  added  in  the  same 
way  if  required.  The  splice  (Fig.  8)  was  used  in  the  false-work  for  the  erection  of  the  Pough- 
keepsie  Bridge,  and  is  said  to  have  proven  very  stiff  and  strong,  and  to  have  given  great  satis- 
faction. 


Sn — ' — ' — ' — ' — '\j  ;(    ' — '  i  '    ' — r 

/*f  x*5V 

^1    I    I    I   I    10    i    I    I'M    !    IT.".-.    '  .3 

l*~  ~  •"  ^—i        ™ ~  -*  — • — —     —  £  Q  — .  —  —     — —  —  ^  — —  ___^j 


FIG.  8. — PILE-SPLICE,  POUGHKEEPSIE  BRIDGE. 

Piles  are  also  joined  together  by  a  long  iron  dowel  (Fig.  9).     The  dowel  is  only  of  use  to 
prevent  lateral  movement,  and  cannot  be  expected  to  keep  the  piles  in  line  at  all,  on  account 
of  the  great  leverage.     A  wrought-iron  dowel  i£  inches  in  diameter  by  2 
feet  long  is  of  good  proportions.     It  is  also  better  to  band  the  end  of  the 
larger  pile  with  a  wrought-iron  ring  to  prevent  its  being  split.     A  broad 
band  encircling  a  portion  of  both  piles  (Fig.  10)  is  not  very  serviceable 
unless  it  be  fastened  so  securely  that  it  cannot  move  from  one  pile  to  the 
other,  as  unless  this  is  done  it  is  usually  found   to  be  wholly  on   either 
FIG.  9.  FIG.  10.    one  of  the  two  piles  after  the  first   few  blows.     If  a  few  track  spikes 

PILE  -SPLICES.  are  driven  into  the  piles  above  and  below  the  ring,  this  movement  will  be 
prevented.  The  abutting  end  of  the  lower  pile  should  be  as  large  as  practicable,  and  where 
the  piles  are  of  such  timber  as  to  require  the  wasting  of  a  large  part  of  the  pile  to  secure  a 
reasonable  diameter,  the  contract  should  name  a  price  for  such  wasted  material.  However, 
no  waste  should  be  paid  for  as  such  which  can  be  used  in  any  other  place  on  the  same 
contract,  and  that  which  is  paid  for  should  be  considered  as  belonging  to  the  company,  and 
the  contractor  not  be  allowed  to  remove  it  unless  he  is  willing  to  repurchase  it. 

It  has  sometimes  been  fo'und,  where  the  ground  is  very  soft  and  runny,  and  it  is  diffi- 
cult to  drive  the  piles  to  a  firm  foundation,  that  if,  after  driving  to  a  moderate  depth,  they 
are  allowed  to  stand  quiet  for  a  day  or  so,  the  surrounding  material  will  settle  against  them, 
and  they  will  safely  bear  their  load,  being  supported  by  the  friction  on  their  sides. 

Previous  to  driving,  the  piles  should  have  the  end  that  is  to  penetrate  the  ground  some- 
what sharpened.  The  point  shown  in  Fig.  1 1  is  a  very  good  shape. 

Whenever  the  pile  is  likely  to  encounter  logs,  bowlders,  or  any  material  likely  to 
split  it,  or  to  broom  the  point  to  an  injurious  degree,  it  is  usual  to  protect  it  either 
by  a  cast-  or  a  wrought-iron  shoe.  These  shoes,  however,  are  apt  to  strip  off  in 
driving. 

Figs.  12  to  15  show  some  of  the  different  forms  of  cast-iron  shoes  used,  and  Figs. 

FIG.  ii. 
16  and  17  some  of  those  of  wrought-iron.    The  one  in  Fig.  14  is  cast  around  a  i-inch     PILE. 

square  drift-bolt.     This  is  preferable  to  the  one  in  Fig.  12,  in  which  the  pin  is  of  cast-    POINT- 
iron  as  well  as  the  point,  as  the  pin  is  liable  to  break  off  just  where  it  joins   the  point.      Fig. 
15  shows  probably  the  best  form  of  cast  shoe.     The  dowel  is  a  drift-bolt,  as  in  Fig.  14;  while 
in  addition  there  is  a  recess  about  2  inches  deep,  with  walls  from  i  inch  to  i£  inches  thick, 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


cast  in  the  top  of  the  point.  The  ring  so  formed  not  only  helps  to  keep  the  shoe  from  being 
forced  off  laterally,  and  thus  relieves  the  pin  of  some  of  the  strain,  but  it  also  aids  in  prevent- 
ing the  pin  from  splitting  the  end  of  the  pile  in  case  much  lateral  force  is  exerted  against  the 
point.  Fig.  16  shows  a  wrought-iron  shoe.  The  point  is  of  small  size  and  has  four  straps 


FIG.  13. 


FIG.  14. 


FIG.  15. 


FIG.  16. 


CAST-  AND  WROUGHT-IRON  SHOES  FOR  PILES. 

extending  up  the  faces  of  the  point  of  the  pile,  each  of  which  is  fastened  to  pile  by  two  spikes. 
Whenever  the  top  of  the  pile  is  likely  to  be  injured  by  the  hammer  it  should  be  encircled 
by  a  heavy  wrought-iron  ring  while  being  driven.     Such  a  ring  is  shown  in  Fig.  18.     These 
rings  may  be  removed  as  soon  as  the  driving  is  completed,  and  used  over 
and  over  again.     The  temperature  at  the  time  of  driving  appears  to  have 
considerable  influence  over  the  tendency  of  the  piles  to  split,  and  espe- 
cially is  this  the  case  with  certain  kinds  of  timber,  such  as  white  and 
Norway  pine.     The  colder  the  weather  the  greater  the  tendency.     This 
is  probably  the  case  only  when  the  temperature  is  below  freezing.     When 
the  piles  have  been  driven  with  the  butts  up  in  water,  the  elevation 
of  the  surface  of  which  is  liable   to  much  change,  the  ice  in  the  winter- 
time has  been  known  to  draw  them  in  very  cold  climates. 
FIG.  18.— RING  FOR  PILE.  In  driving  it  is  always  preferable  to  have  a  heavy  hammer  with  a 

short  fall,  but  difficulties  of  transportation  prevent  the  use  of  very  heavy  hammers  in  some 
cases.  Ordinarily  a  hammer  of  2000  Ibs.  weight  falling  25  feet  is  a  good  proportion,  but  a 
heavier  hammer  with  less  fall  is  better.  The  piles  should  not  settle  more  than  from  I  inch  to 
3  inches  at  the  last  blow,  and  better  if  much  less. 

Where  the  bridge  is  very  long,  and  hence  the  number  of  piles  large,  it  becomes  exceed- 
ingly important  to  determine  with  reasonable  accuracy  the  approximate  lengths  of  the  piles 
and  the  number  of  each  different  length  required.  To  accomplish  this  end  a  plan  was 
adopted  in  the  building  of  the  Northern  Pacific  R.R.  Bridge  over  the  St.  Louis  River  at 
Duluth,  Minn.,  which  is  said  to  have  proven  very  satisfactory  indeed.*  Test-piles  were  driven 
every  300  feet  along  the  centre-line,  and  where  any  great  difference  in  penetration  was  noticed 
an  intermediate  pile  was  driven.  These  piles  were  driven  from  a  scow,  and  the  distance 
measured  by  tying  a  rope  to  the  last  pile  driven.  The  correct  position  of  each  pile  was 
finally  determined  by  triangulation.  A  complete  record  of  the  details  of  the  test-piles  was 
kept  under  the  following  form :  f 

*  "  Pile-driving,"  E.  H.  Beckler,  Eng.  News,  vol.  xvi.,  p.  83. 
f  This  form  has  been  very  slightly  modified  by  the  author. 


10 


A    TREATISE  ON    \VOODEN    TRESTLE  BRIDGES. 


Sta. 

No.  of 
Pile. 

to 

p 

V 

Dia. 
of 
Top. 

Diam. 
of 
Butt. 

JS        u 

a~S 

S°| 

Dist. 
Driv- 
en. 

Elev. 
Top 
of 
Pile. 

Elev. 
Point 
of 
Pile. 

No.  of 
Blows. 

Fall  of 
H..m- 
mer. 

Wt. 

of 
Ham- 
mer. 

Penetration  for  each  ten  consecutive  blows. 

40 

50 

60 

70 

so 

90 

100 

no 

1  20 

"3° 

140 

'5° 

80  +  23.7 

16 

52' 

8i" 

i  Si" 

9-7' 

39-3' 

84.8' 

3=.S' 

1  2O 

20' 

Ibs. 
2256 

13" 

14" 

16" 

17" 

15" 

12" 

12" 

The  fall  of  the  hammer  given  is  for  the  last  ten,  twenty,  or  thirty  blows.  Each  pile  was 
intended  to  be  driven  until  it  fulfilled  the  requirements  of  the  specifications;  i.e.,  penetration 
not  to  exceed  I  inch  under  the  last  blow  of  a  2000  Ibs.  hammer,  with  a  fall  of  20  feet  or 
equivalent.  The  notes  relating  to  the  size  and  driving  of  the  piles  were  taken  by  the 
inspector  at  the  time ;  elevations  by  the  engineer  afterwards.  A  profile  was  then  made  up 
from  these  notes,  and  the  piles  ordered  according  to  the  lengths  measured  upon  it.  It  was 
found  that  this  method  gave  excellent  results,  there  being  but  few  discrepancies  between  the 
actual  material  when  in  place  and  that  ordered.  The  waste  of  material  was  consequently 
reduced  to  a  minimum. 

A  permanent  record  of  all  the  final  work,  in  detail,  should  always  be  made  at  tke  time 
construction  is  going  on,  for  the  future  use  of  the  Maintenance  of  Way-Department.  An 
excellent  form  of  such  a  record,  as  used  on  the  above  work,  is  given  below.* 


NORTHERN   PACIFIC   RAILROAD   COMPANY. 
PILE-DRIVING   RECORD,   BRIDGE   NO.    l6o. 


Date 
and 
Station. 

Number  of 
Bent. 

Number  of 
Pile. 

Kind 
of 
Timber. 

"o 

fld 

is 

2 

Diameter 
of  Butt. 

Diameter 
of  Top. 

Length  below 
Cut-off. 

Length  of 
Cut-off. 

Elevation  of 
Ground. 

Elev.  of 
Point  of  Pile. 

Distance 
driven. 

Fall. 

Number  of 
Blpws. 

Penetration  for  given 
number  of  Blows. 

Dec.  27. 

ft. 

ins. 

ins. 

ft. 

ft. 

ft. 

ft. 

ft. 

ft. 

114  +  30 

42 

I 

Wh.  P. 

40.0 

17 

14 

3'-4 

8.6 

76.2 

66.4 

9.8 

2O 

85 

20  j 

10" 

40 

10" 

60 

5" 
70 

4" 
80 

i" 
8S 

"4  +  30 
Jan.  10. 

42 

4 

Wh.  P. 

40.0 

16 

II 

33-° 

7.0 

76.2 

64.8 

"•3 

2O 

60 

2O  | 

10" 
3° 

7" 
40 

7" 
50 

7" 
60 

112+65 

53 

3 

Wh.  P. 

42.0 

15 

13 

36.0 

6.0 

74-8 

6l.8 

13.0 

18 

5° 

\ 

20 

u 
3° 

i  r 
40 

9 

50 

The  actual  cost  and  rate  of  driving  the  piles  on  this  trestle  was  as  follows : 
SUMMARY   OF  WORK  OF  ONE   DRIVER. 


Dates. 

Number 
of 
Days. 

Number  of 
Piles 
Driven. 

Lin.  ft.  of 
Piles  driven. 

Number  of 
Piles  driven 
Daily. 

Lin.  ft.  of 
Piles  driven 
Daily. 

Contractor's 
Cost  of 
Driving. 

Average  Cost 
of  Driving 
per  lin.  ft. 

1884. 

Piles  23'  to  45'  long,  Dec.  ) 
u  to  31,        .         .         .  f 

ioi 

202 

6520$ 

I9i 

621 

$454-43 

$0.069691 

1885. 

Jan.  i  to  5  and  10  to  14.  / 
Piles  over  45'  long,       .  ) 

5* 

134 

5785 

23T3* 

I006 

212.57 

0.0367 

Jan.  5  to  10  and  14  to  31, 

141 

364 

21535 

25-rV 

1485 

539-6i 

0.02506 

Feb.  i  to  28,      . 

19! 

379 

25036 

'91 

1268 

747-74 

0.0298 

March  I  to  5,    . 

3i 

73 

4789 

22* 

1473 

135-75 

0.0284 

Average  cost  per  lin.  ft.,  piles  less  than  45  feet  long, 
«      «      «     «       .«      over    "    45     "      " 


$0.0542 
0.0277 


*  This  form  has  been  very  slightly  modified  by  the  author. 
t  Some  delay  on  shore. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


n 


This  is  the  actual  cost  of  driving  after  the  piles  were  delivered  at  the  pile-driver. 

The  best  record  was-  120  piles  =  6600  ft.  in  four  consecutive  days.  Contractors  were 
Winston  Bros,  of  Minneapolis. 

This  record  may  be  taken  as  a  fair  average,  and  under  like  conditions  may  be  used  as  a 
basis  to  estimate  both  time  and  cost.  The  trestle  was  a  long  one  across  a  bay,  which  was 
completely  frozen  over. 

In  making  up  approximate  estimates  of  the  cost  of  piling  and  trestles,  when  exact  data  is 
not  at  hand,  the  following  figures  may  be  used  with  a  very  close  approach  to  accuracy,  as 
they  are  based  on  actual  contract  prices  : 

TABLE  VII. 

Prices  of  Trestle  Material  in  Different  Sections  of  North  America. 


Material. 

Texas. 

Virginia. 

Indiana. 

Washington. 

Halifax 
Harbor. 

1888. 

1889. 

1890. 

1879-81. 

1888. 

1884-85. 

Average  penetration  of  Piles  on  land. 
Piles  per  lin.  ft.  in  place,       .... 

* 
35C. 

$40 
$30 

t 

$30' 
$30' 

I 

$30' 

$30' 

12  ft.2 
25C. 

$25  to  $30 
$13  to  $16 

Sic. 

I 

9c. 

$23 

6c.  to  7c. 

ir 

<  Hemlock, 
I    $16.47 

Wh.  $26.00 

Round  Timber  per  lin.   ft.  erected  (round- 
timber  trestle)          
Dimension  Timber  per  M,  B.  M.,  erected,   . 
Oak  

Pine  

Heart  Pine  (Va.  Pine)  
Cattle-guard  Timber  per  M,  B.  M.,  erected, 
Bolts  and  Nuts  per  lb.,  ..... 

1  Includes  iron. 

2  This  may  be  taken  as  the  average  penetration  of  piles  in  the  clay  of  the  Indiana  prairies.     On  the 
Illinois  prairies  the  average  penetration  may  be  taken  at  about  18  feet. 

*  C.  A.  Wilson. 

t  Maintenance  of  Way  Dept.,  Norfolk  &  Western  R.  R. 

\  New  River  Plateau  R.  R.,  an  extension  of  the  N.  &  W.  R.  R. 

§  I.,  D.  &  S.  Ry.,  E.  A.  Hill.  On  Indiana  section  lumber  is  very  scarce,  and  oak  bridge-timber  twenty 
to  fifty  feet  long  costs  from  $13.50  to  $50  per  M,  B.  M. 

Not  erected  materials  cost  as  follows,  f.o.b. ;  Piles  in  ordinary  lengths,  and  from  10  to  12  in.  in  diam- 
eter at  the  smaller  end,  from  i3ic.  to  I5c.  per  lin.  ft.  Bolts  3c.  and  cast  washers  2c.  per  lb. 

||  Vancouver,  Klickitat  &  Yakima  R.  R.,  Eng.  News,  June  9,  1888. 

1  See  R.  R.  Gazette,  1886,  p.  242. 

As  soon  as  the  pile-driving  has  advanced  a  short  distance,  the  preparation  of  the  top  of 
the  piles  for  the  reception  of  the  cap  is  begun.  The  elevation  of  the  top  of  the  pile  is  marked 
by  a  line  on  the  face  of  one  or  two  piles  in  each  bent  by  the  engineer. 


FIG.  iq. — MARKING  PILES  FOR  CUTTING  OFF. 


12 


A    TREATISE  ON    WOODEN    TRESTLE   BRIDGES. 


A  narrow  plank  having  a  straight  upper  edge,  and  long  enough  to  extend  entirely  across 
the  bent,  is  then  nailed  on  each  side  of  the  piles  (Fig.  19),  and  the  top  cut  off  level  or  cut  in  far 
enough  to  form  the  tenon.  A  cross-cut  saw  worked  by  two  men  is  very  convenient  for  this 
work. 

There  are  several  ways  of  fastening  the  caps  to  the  piles,  —  by  mortise  and  tenon,  by  drift- 
bolts,  or  by  dowels.  For  solid  caps,  a  tenon  3  ins.  thick,  8  ins.  wide,  and  5  ins.  long  is  a 
very  good  size.  The  edges  around  the  top  of  the  tenon  should  be  cham- 
fered (Fig.  20).  When  tenons  are  employed,  it  is  customary  to  use 
wooden  pins  (treenails)  for  fastening  the  parts  together.  The  pins  may  be 
of  any  tough  hard  wood.  White  oak  and  locust  answer  all  the  require- 
ments very  well.  They  ought  to  be  from  I  in.  to  i£  in.  in  diameter,  and 
slightly  tapered  —  say  %  in.  to  \  in.  (Fig.  20).  The  hole  in  the  tenon 
should  be  somewhat  nearer  the  top  of  the  pile  than  that  in  the  cap  is  to 
the  edge,  so  that  the  pin  when  driven  in  will  draw  the  two  parts  tightly 
together.  Bolts,  |  in.  in  diameter,  have  been  sometimes  used  in  place  of 
pins,  but  are  not  as  desirable  ;  in  fact,  their  use  should  be  discouraged. 


____  /2r.  ..... 


FIG.  21. — FASTENING  CAP  TO  PILES. 


Fm.  20.—  PILE  TENON  When  drift-bolts  or  dowels  are  employed  the  top  of  the  pile  is  cut  off 
AND  TREENAIL.        square.     Dowels  frequently  extend  through  the  cap  ;  generally  one,  some- 
times two,  drift-bolts  or  dowels  per  pile  are  used  ;  one  is   amply  sufficient.     Details  of  the 
different  kinds  of  drift-bolts  and  of  dowels  are  given  in  full  in  the  chapter  on  iron  details. 

Sometimes  a  mortise-and-tenon  joint  is  employed  for  the  outer  piles,  with  the  inner  piles 
cut  off  square,  and  drift-bolted  as  shown  in  Fig.  21. 

There  is  still  another  method  of  fastening  the  caps  to  the 
piles,  which  is  rapidly  becoming  the  general  practice,  which  is 
by  the  use  of  split  caps.  Instead  of  using  a  single  piece  of 
timber  for  the  cap,  two  pieces,  each  half  the  size,  are  employed. 
For  instance,  a  single  12-in.  by  12-in.  stick  is  replaced  by  two 
6-in.  by  J2-in.  sticks.  A  tongue  or  tenon  about  3  in.  thick  and  the  full  width  of  the  pile  is 
formed  on  its  top,  and  one  of  these  pieces  placed  on  either  side  and  held  in  place  by  one,  or 
better  two,  f-in.  or  i-in.  bolts  passed  through  at  each  pile.  The  sticks  should  not  be  notched, 
and  they  should  rest  evenly  on  the  edges  formed  on  top  of  the  piles.  This  form  of  cap  is 
claimed  to  have  many  advantages,  among  which  may  be  mentioned  — 

ist.  On  account  of  smaller  size,  better  timber  may  be  obtained  and  at  less  cost. 

2d.  Repairs  may  be  made  with  ease  and  great  economy  in  time  and  labor. 

3d.  Traffic  need  not  be  interfered  with  or  endangered  while  repairs  are  being  made. 

4th.  The  caps  may  be  replaced  without  cutting  or  injuring  any  other  part  of  the  structure 
in  the  least. 

5th.  Economy  in  material,  because  it  is  not  necessary  to  replace  the  whole  cap  unless 
both  sticks  are  decayed  or  injured,  but  only  that  part  which  is  no  longer  in  a  serviceable  con- 
dition. 


CHAPTER  III. 
PILE-DRIVERS. 

WHILE  there  are  a  great  many  forms  and  styles  of  pile-driving  apparatus,  there  are  but 
three  principal  methods  of  sinking  piles  in  general  use.  These  are : 

1st.  To  force  the  piles  into  the  ground  by  allowing  a  heavy  weight  to  fall  upon  them 
when  in  an  upright  position,  or  by  striking  heavy  blows  by  some  means  upon  their  heads  or 
tops. 

2d.  To  sink  the  piles  by  means  of  a  jet  of  water. 

3d.  To  screw  the  piles  (which  are  either  of  iron  or  else  have  a  special  shoe)  into  the 
ground. 

As  the  first  of  these  methods  is  the  one  most  extensively  used,  we  may  say  almost 
universally, — and  the  one  most  generally  applicable  to  trestle-building,  we  will  confine  our- 
selves strictly  to  a  description  of  several  different  forms  of  apparatus  for  accomplishing  the 
desired  end  by  this  means. 

The  particular  kind  of  machine  to  be  used  will  depend  upon  the  special  conditions 
surrounding  the  case. 

In  very  rough  and  bad  country  the  simpler  and  lighter  the  machines  consistent  with  the 
requirements  of  the  work  the  better.  Sometimes  merely  a  pair  of  leads  with  the  necessary 
stays  or  back-bracing  to  give  them  the  required  stiffness,  a  common  hoisting-machine  (usually 
horse-power  in  such  a  case  as  this),  with  the  hammer,  ropes,  and  blocks,  are  all  that  are 
carried  from  place  to  place.  Everything  is  made  as  simple  as  possible,  and  so  that  it  can  be 
taken  apart  for  transportation.  Sometimes  the  apparatus  is  mounted  upon  wheels,  so  that 
it  may  be  folded  down  and  drawn  around  by  a  team  of  horses.  When  the  scene  of  action  is 
reached  the  leads  are  merely  raised  up.  This  lifts  the  wheels  off  the  ground.  The  base  is 
then  lashed  to  a  couple  of  12-in.  logs,  and  as  soon  as  the  hoister  is  put  in  position  and  the 
tackle  arranged,  everything  is  ready  for  the  commencement  of  the  driving. 

Where  transportation  is  not  too  difficult,  it  is  preferable  to  use  a  more  complete  driver. 
A  steam-boiler  and  hoister  is  substituted  for  the  horse-power  one.  With  this  arrangement 
the  driving  proceeds  more  rapidly  and  at  less  cost. 

When  many  piles  have  to  be  driven  in  navigable  waters  the  driver  is  mounted  on  a  scow. 

Figs.  22  to  28  illustrate  a  machine  of  the  very  latest  model,  and  one  of  the  heaviest  in 
New  York  Harbor.* 

"The  hull  is  56  ft.  6  in.  long,  and  23  ft.  6  in.  wide,  over  all ;  each  of  the  sides  of  the  hull 
is  made  of  four  pieces  of  yellow  pine,  the  two  lower  each  8  in.  X  14  in.,  the  third  7  in.  X 
14  in.,  the  top  piece  6  in.  X  14  in.,  all  securely  tied  by  through-bolts ;  the  bow  planking  is 

*  From  "  Bearing  Piles,"  by  Rudolph  Hering,  N.  Y.,  1887. 

13 


i4  A    TREATISE  ON   WOODEN   TRESTLE  J3 RIDGES. 

oak  5  in.  thick,  the  bottom  and  end  plank  yellow  pine  3  in.  thick.  The  bow  is  further 
strengthened  by  a  i6-in.  X  l6-in.  cross-timber  at  top,  and  at  the  stern  is  an  8-in.  X  12-in. 
cross-timber  of  yellow  pine.  Oak  is  used  on  the  bow,  as  being  better  adapted  to  stand  the 


constant  wear  of  the  piles  hauled  against  it ;  and  to  prevent  knots  or  inequalities  on  the  piles 
interfering  with  their  position  under  the  hammer,  the  bow  planking  overhangs  6  in.  in  its 
total  height. 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES.  15 

"  The  chief  end  in  the  design  of  a  hull  for  a  floating  pile-driver  is  to  obtain  longitudinal 
stiffness,  so  that  the  strains  between  the  bow  and  engine  may  be  properly  distributed.  To 
this  end  our  hull  is  strengthened  lengthwise  by  four  wooden  bulkheads  or  kelsons,  each  6  in. 
thick  (Fig.  23),  and  braced  laterally  by  four  sets  of  X  braces  of  6-in.  X  6-in.  timber.  The  hull 
is  further  braced  in  the  centre  by  two  3-in.  X  12-in.  Y.  P.  braces,  and  tie-rods  or  'hog- 
chains'  of  iron  if  in.  in  diameter.  Wale-pieces  and  fender-plank  3  in.  thick  protect  the 
outside  of  the  hull  against  chafing;  .the  deck  has  a  '  crown  '  of  about  6  in.  in  its  total  width." 

"The  hammer-guides  are  made  of  two  pieces  of  12-in.  X  12-in.  Y.  P.  67  ft.  long  from  out 
to  out,  with  inside  guides  of  5  in.  X  4  in.  stuff  protected  by  plate-iron  \  in.  thick;  f-in.  bolts 
with  countersunk  heads  fasten  the  inner  guides  to  the  main  sticks,  and  at  the  same  time 
secure  the  iron-work  to  the  same.  The  bottom  of  the  main  guides  are  connected  with  the  12- 
in.  X  12  in.  bed-pieces,  shown  in  Fig.  24,  by  two  timber-knees,  and  are  tied  at  top  by  the  cap 
shown  in  Fig.  27. 

"  The  dimensions  and  general  arrangement  of  the  back-bracing  is  fully  shown  in  Figs.  22 
and  24 ;  the  bolts  used  in  this  portion  of  the  framework  are  £•  in.  diameter.  The  side-braces 
are  round  timbers  16  in.  diameter  at  the  butt,  and  they  are  anchored  to  the  hull  by  two  heavy 
timber-knees  to  each.  The  bed-pieces,  as  shown  at  Fig.  24,  are  fastened  down  to  the  hull  by 
four  bolts,  each  I  in.  in  diameter,  the  forward  bolts  passing  through  the  l6-in.  X  i6-in.  oak 
piece  on  bow,  and  the  after-bolts  passing  into  a  cross-timber  6  in.  X  14  in.,  as  shown  at  Fig. 
25.  The  foot  of  the  back-bracing  is  secured  to  the  bed-timbers  by  one  i-in.  strap-bolt  in 
each  timber,  the  strap  portion  of  bolt  being  2  in.  X  i  in.  in  section.  A  -f-in.  through-bolt 
ties  the  three  braces  together. 

"  The  iron  stay-rods  running  from  head  of  guides  to  after  part  of  hull  are  two  in  number, 
and  are  each  I  in.  in  diameter. 

"  The  hoisting-sheaves  on  top  are  two  in  number,  placed  side  by  side.  They  are  12  in. 
in  working  diameter,  15^  in.  from  out  to  out,  and  3^  in.  wide;  and  the  pin  passing  through 
them  is  2\  in.  diameter  at  the  sheaves,  and  2  in.  diameter  in  the  boxes.  Experience  teaches 
that  these  proportions  are  none  too  great  to  stand  the  severe  work  frequently  put  upon  it  in 
hoisting  heavy  weights  and  tearing  out  timber.  The  fall-rope  attached  to  the  hammer  is  2  in. 
in  diameter,  and  the  'runner'  used  in  hoisting  up  piles  is  if  in.  diameter. 

"  The  hoisting-engine  is  a  double-drummed  Mundy  engine  of  a  nominal  25  horse-power. 

"  Fig.  26  shows  the  hammer  used  with  this  machine.  The  drawing  is  sufficient  to  show 
its  general  design.  The  weight  is  3300  Ibs. 

"  Fig.  28  shows  the  method  of  attaching  the  two  $-in.  X  12-in.  horizontal  braces  to  the 
round  side-braces,  as  further  shown  in  Fig.  23." 

In  double-tracking  a  single-track  road,  or  in  repairing  trestles  in  use,  a  form  of  driver 
mounted  on  a  flat-car  is  found  to  be  very  convenient  and  economical.  Figs,  29  to  32  show 
the  details  of  one  of  the  latest  designs  for  a  driver  of  this  kind.* 

It  was  constructed  by  the  Missouri  Pacific  Railway,  "  with  the  purpose  of  obtaining  a 
machine  which  could  work  effectively  on  piles  at  a  further  distance  from  the  road-bed  than 
usual.  The  design  was  worked  out  jointly  by  the  Bridge  and  Building  Department  and  the 
Car  Department. 

Railway  Review,  October  25th  and  November  8th,  1890. 


i6 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


i8 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


ig.  30  shows  the  framing  of  the  upper  deck  of  the  pile-driver  and  of  the  cab.  It  will 
be  noticed  that  the  main  timbers  are  very  long — 57  ft.  8  in.,  and  are  5  in.  X  I2|  in.  in  thick- 
ness. The  side-sills  are  6f  in.  X  12^  in.,  and  43  feet  long.  From  the  centre  of  the  track  on 
which  the  platform  revolves  to  the  centre  of  the  leads  is  a  distance  of  33  ft.,  and  in  order  to 
reach  work  which  is  located  16  ft.  to  one  side  of  the  centre  of  the  track  the  driver  must  swing 
to  an  angle  of  about  30°  from  the  track.  The  upper  platform  travels  upon  three  circular 
tracks.  The  first  is  a  complete  circle,  having  a  diameter  of  nearly  9  ft.,  and  as  the  car  is  9  ft. 
wide  and  the  upper  platform  10  ft.,  this  track  is  fixed.  The  next  circle  has  a  diameter  of 
13  ft.  3  in.,  and  is  composed  of  four  pieces  of  rail  of  the  ordinary  section,  two  of  which  are 
firmly  secured  to  the  car  platform,  while  the  other  two  pieces  overhang  the  sides  of  the  car, 
and  are  removed  while  the  pile-driver  is  in  transit.  When  in  use  they  are  supported  in 
position  by  two  wrought-iron  swing-brackets  fastened  to  the  outside  face  of  each  side-sill,  and 
are  also  secured  to  fixed  sections  by  fish-plates.  The  third  circular  track  has  a  radius  of  14  ft. 
5  in.,  and  is  a  bar  of  iron  4  X  I  in.  This  track  is  not  carried  beyond  the  sides  of  the  car.  The 
wheels  which  bear  upon  the  two  smaller  circles  are  attached  directly  to  a  heavy  flooring  on 
the  under  side  of  the  platform,  and  as  far  as  possible  they  are  placed  in  the  vicinity  of  a 
longitudinal  sill,  so  as  to  give  them  as  solid  a  bearing  as  possible.  The  rollers  which  bear  on 
the  outer  one  of  the  three  tracks  are  secured  to  the  under  side  of  a  heavy  transverse  bolster, 
which  is  composed  of  three  pieces  of  wood  with  three  wrought-iron  plates  6  in.  X  f  in.  in 
section  intervening  between  them,  the  bolster  being  6  in.  X  io£  in.  in  section.  The  bolster 
at  the  centre-pin  is  wood  12  in.  wide  and  9  in.  deep,  and  is  trussed  by  two  rods  each  an  inch 
in  diameter. 

"  The  construction  of  the  leads  and  ladder  will  be  best  understood  by  a  reference  to  Fig. 
29.  The  leads  are  36  ft.  long,  and  are  hinged  to  a  heavy  triangular  framework,  a  detail  of 
which  is  shown  in  Fig.  31.  A  sole-plate  10  in.  X  f  in.  in  section  is  secured  to  the  upper  face 


FIG.  31.— CAR  PILE-DRIVER,  MISSOURI  PACIFIC  RY.     (DETAILS  OF  LEADS.) 

of  the  longitudinal  sills  which  support  the  beam.  The  hinge-frame  is  secured  to  this  plate, 
and  consists  of  plates  6  in.  X  $  in.,  reinforced  by  angle-irons.  The  inner  faces  of  the  leads 
are  protected  by  steel  channel-irons  extending  up  from  the  bottom  end  for  a  distance  of  26 
ft.  These  afford  a  good  bearing  for  the  hammer,  which  is  planed  out  to  fit  them. 

"The  car  upon  which  the  pile-driver  is  carried  is  shown  in  Fig.  32.  It  is  an  exceedingly 
heavy  car,  as  will  be  seen  from  an  inspection  of  the  drawing.  It  is  30  ft.  long  and  9  ft.  wide, 
and  very  strongly  trussed.  The  rack  for  moving  the  upper  deck  is  seen  in  this  view,  and 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES.  19 

requires  no  explanation.  When  the  car  is  in  transit,  four  jack-screws,  one  at  each  corner  of 
the  car,  are  adjusted  against  suitable  sockets  on  the  under  side  of  the  upper  deck,  so  as  to 
steady  the  entire  superstructure.  At  the  same  time  the  upper  deck  is  prevented  from  swing- 
ing out  of  a  longitudinal  position  by  means  of  suitable  hooks  attached  to  the  upper  deck, 
which  engage  eye-bolts  in  the  ends  of  the  car.  When  the  pile-driver  is  at  work  these  jack- 
screws  are  released,  and  the  heavy  screws  seen  extending  down  through  the  floor  of  the  car 
are  made  to  bear  upon  the  truck  frames.  This  prevents  any  undue  strain  on  the  trucks 
springs,  and  also  any  unsteadiness  which  might  be  caused  from  their  elasticity." 


FIG.  32.— CAR  PILE-DRTVER,  MISSOURI  PACIFIC  RY.     (DETAILS  OF  CAR.) 

"  The  hammer  weighs  2397  Ibs.,  and  is  operated  by  a  Lidgerwood  hoisting-engine.  As 
will  be  seen  from  the  illustrations,  the  upper  platform  of  the  pile-driver  is  so  long  in  compari- 
son with  the  car  which  carries  it  that  a  flat-car  at  each  end  is  necessary  for  its  transportation. 
One  of  these  cars  is  constructed  for  the  purpose,  and  carries  a  supply  of  water  and  coal,  and 
any  other  material  which  may  be  necessary.  This  is  attached  at  the  cab  end  of  the  pile-driver, 
and  the  one  at  the  other  end  is  a  common  flat-car." 

In  use  the  ordinary  drop-hammer  tends  to  batter  the  heads  and  split  the  piles.  It  is 
claimed  that  the  steam  pile-hammer  overcomes  this  objection  to  a  very  large  extent,  and  thr.t 
it  will  drive  the  piles  more  rapidly. 

"After  the  steam-hammer  begins  operation  the  blows  are  so  rapid — 70  to  100  per 
minute — that  the  earth  once  disturbed  has  no  time  to  settle,  and  the  pile  sinks  through  it  in 
somewhat  the  same  manner  as  it  would  when  the  earth  is  loosened  and  held  in  suspension  by 
a  water-jet."  * 

*  "  Builders  and  Contractors'  Engineering  and  Plant :  "   The  Sanitary  Engineer. 


20 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


Messrs.  Ross  &  Sanford  drove  on  an  average  83  piles,  having  a  penetration  of  17  ft.,  in 
material  mostly  sand  and  oyster-shells,  per  day  of  ten  hours,  with  one  of  these  steam-hammers. 
There  were  1459  piles  in  all  in  the  work,  which  was  a  pile-dike  in  the  Passaic  River,  N.  J. 
The  best  ten-hours'  work  was  121  piles.  The  best  work  in  the  same  time  with  an  ordinary 
driver  was  63  piles.  In  the  matter  of  expense  the  steam-hammer  costs  more  for  steam  than 

the  ordinary  driver,  but  this  is  more  than  offset 
by  the  saving  in  pile-bands,  rope,  and  the  num- 
ber of  men  on  the  machine. 

Figs.  33  to  37  show  such  a  hammer,  and  the 
method  of  using  it.  The  following  reference- 
letters  will  aid  in  enabling  one  to  understand  the 
construction  of  the  machine  : 

A  A.  Ten-inch  I-beams  forming  the  sliding- 
frame  within  which  the  hammer  H  L  slides. 

B.  Cross-girder  riveted  to  the  upper  ends  of 
the  I-beams  (A)  by  means  of  which  and  the  bail 
(s)  the  whole  apparatus  is  raised  or  lowered  for 
adjustment  to  the  head  of  the  pile. 

C.  Hollow    piston-rod    hung    loosely    on    a 
collar  through  a  hole  in  the  cross-girder  (B). 

D.  The  steam-chest,  supported  by  the  cross- 
girder   (B)    and    covering    the    opening    of    the 
piston-rod  (c). 

E.  Piston-head  and  plug  of  the  end  of  the  hollow  piston-rod  (c). 

F.  Steam-openings  in  the  hollow  piston-rod  (c)  through  which  steam  passes  to  the  space 
(G)  surrounding  the  rod. 

G.  Annular  space  (between  the  piston-rod  and  the  interior  of  the  hammer)  which  forms 
the  steam-cylinder. 

H.  Hammer-cylinder. 

I.  Cylinder-cover  with  stuffing-box. 

J.  Foot-block  or  bonnet  casting  riveted  to  the  lower  ends  of  the  I-beams  and  forming  the 
lower  part  of  the  sliding-frame. 

K.  Conical  opening  through  the  foot-block  (j)  shaped  to  receive  the  head  of  the  pile. 

L.  Cylindrical  prolongation  of  the  hammer-cylinder  (H),  forming  the  hammer-head. 

M.  Lever  which  works  the  steam-valve. 

N.  Fulcrum  for  the  lever  (M)  bolted  to  the  face  of  the  girder  (B). 

O.  Attachment  of  the  lever  to  the  valve-stem. 

P.  Upper  trip,  which  throws  the  valve-stem  in  and  supplies  steam  to  the  cylinder  (G). 

Q.  Lower  trip,  which  throws  the  valve-stem  out  and  exhausts  the  steam.  (P  and  Q  are 
both  attached  to  the  hammer-cylinder.) 

R.  Vent  for  air  and  condensed  water. 

S.  Bail  by  which  the  whole  machine  is  lifted. 

T.  Connection  of  steam-hose  with  steam-chest. 


FIG.  33.— STEAM  PILE-HAMMER  IN  OPERATION. 


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21 


End-projcciion, 
Valre  A. 


Side-projection, 
Valve  B. 


tzn 


Clamps  D. 

FIG.  37.— BALANCE- VALVE. 
FIGS.  34  TO  37.— DETAILS  OF  CRAM'S  STEAM  PILE-HAMMER. 


22  A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 

U.  Springs  to  guard  foot-block. 

V.  Balanced  steam-valve. 

\v.   Set-screw  regulating  travel  of  steam-valve. 

X.  Mouth  of  steam-chest  (D). 

"  Fig.  33  is  a  part  general  view  of  a  scow  pile-driver,  with  the  machine  lowered  and 
resting  on  a  pile. 

"  Fig.  34  is  a  rear  elevation  of  the  machine,  showing  the  valve-tripping  apparatus,  also 
a  sectional  plan  on  line  A  A. 

"  Fig.  35  is  a  central  vertical  section  on  line  B  B. 

"  Fig.  36  is  a  side  view,  also  section  on  O  O. 

"  In  use  the  whole  apparatus  slides  on  a  pair  of  ordinary  ways  or  'leaders,'  being  raised 
or  lowered  by  means  of  the  bail  (s). 

"  When  ready  for  use,  as  shown  in  Fig.  33,  the  hammer  is  at  the  bottom  of  the  frame 
resting  on  the  springs  U, — or,  if  the  pile  is  set  up,  on  the  pile, — the  piston-head  being  at  the 
top  of  the  cylinder.*  These  springs  U  serve  to  catch  any  chance  blow  and  prevent  injury  to 
the  foot-block  (j).  The  hammer-head,  of  course,  projects  through  the  orifice  (K)  in  the  foot- 
block,  and  as  much  as  the  pile-head  enters  the  orifice,  so  much  is  the  hammer-cylinder  pushed 
up,  so  that  its  whole  weight  rests  on  the  pile. 

"  On  the  admission  of  steam  through  the  flexible  hose  attached  to  the  inlet  (T),  it  passes 
through  the  piston-rod  into  the  cylinder  (G),  the  hammer  slides  upwards  in  its  frame  A  B  J  to 
the  extent  of  its  stroke  (or  about  40  inches  for  a  large  machine)  ;  then  the  steam  is  exhausted 
through  the  tripping  of  the  valve,  and  the  hammer  falls,  giving  a  free  blow.  The  upper  trip 
at  once  admits  steam,  and  the  operation  is  quickly  repeated." 

"  Fig.  37  shows  details  of  the  valve  and  steam-chest. 

"  The  valve  itself  is  shown  in  end  projection  at  A,  and  side  projection  at  B,  and  is  a 
hollow  cylinder,  with  open  ends  and  a  ring  Y  cast  around  its  periphery,  with  a  slot  Z  cut 
through  its  shell  near  the  ring,  and  with  the  socket  by  which  it  is  held  upon  the  valve-stem  sup- 
ported by  four  radial  webs  (i)  extending  the  length  of  the  valve  and  attached  to  its  shell.  The 
jamb-nuts  (2)  hold  it  firmly  upon  the  valve-stem,  where  the  valve  is  shown  in  place  in  section 
of  steam-chest  between  lines  V  V.  The  upper  wall  of  the  steam-chest  at  (3)  is  made  hollow 
to  preserve  equal  thickness  of  metal  for  uniform  expansion,  etc.,  and  is  connected  by  openings 
(4)  with  interior  of  steam-chest,  so  that  steam  finds  constant  admission  and  can  circulate  from 
end  to  end  of  steam-chest  in  this  way  as  well  as  through  the  hollow  valve. 

"  The  cylindrical  box  (5)  is  cast  so  as  to  surround  the  valve,  and  connects,  first,  through 
slot  6  with  the  opening  7,  which  joins  the  hollow  piston-rod  leading  to  the  hammer  cylinder, 
and,  second,  with  the  exhaust  orifice  8  through  9,  which  opens  to  the  air.  The  tongue  (10) 
separates  the  box  int.o  two  portions  used  for  exhaust  and  supply  respectively,  each  of  which 
has  an  annular  slot  (8  and  6)  through  the  steam-chest  shell  surrounding  the  valve  shell. 

"  It  will  be  noticed  that  the  only  steam-pressure  on  the  valve  is  outward  from  within  the 
cylindrical  valve-shell,  and  can  exert  no  influence  toward  producing  friction.  In  other  words, 
the  valve  is  so  perfectly  balanced  that  it  works  readily,  whether  with  or  without  steam 
supplied. 


*  Corrected  from  original. 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  23 

"  In  the  drawing  the  valve  is  slid  out,  or  as  it  would  be  thrown  by  the  trip  Q  acting  upon 
the  lever  M  when  it  is  ready  to  fall.  In  other  words,  the  steam  is  being  exhausted  as  the  ring 
Y  straddles  the  two  slots  6  and  8,  and  steam  from  within  the  hammer  cylinder  finds  vent  up 
the  hollow  piston-rod  and  out  the  exhaust-port  (9). 

"  The  complete  action  is  then :  The  hammer  falling,  the  valve  is  thrown  so  the  slot  Z 
covers  6,  while  the  exhaust-slot  8  is  covered  by  metal.  The  steam  from  steam-hose  connec- 
tion T  through  the  hollow  valve-slot,  Z,  6  and  7,  and  hollow  piston-rod  finds  admission  to  the 
interior  of  the  hammer,  which  causes  it  to  rise  until  the  lever  throws  out  the  valve,  and  steam 
is  exhausted  as  before. 

"The  hammer-cylinder  weighs  5500  Ibs.,  and  with  60  to  75  Ibs.  steam  gives  75  to  80 
blows  per  minute.  With  41  blows  a  large  unpointed  pile  was  driven  35  feet  into  a  hard-clay 
bottom  in  half  a  minute. 

"  The  steam-valve  has  a  travel  of  five  eighths  of  an  inch  in  a  steam-jacketed  chest.  The 
length  of  it's  movement  is  adjustable,  so  as  to  suit  the  force  of  the  blows  to  the  work  in  hand." 

The  cost  of  these  drivers  varies  according  to  size  and  weight  of  ram,  as  follows : 

Size.  Weight  of  Ram.  Price.          Width  between  Leaders.  Length  of  Stroke.  Total  Weight.  Total  Length. 

B  5500  Ibs.  $800  27  inches  40  inches  8400  Ibs.  12  feet 

C  3000   "  700  20      "  40      "  5500  "  12     " 

D  2000   "  500  20      "  24      "  4200   "  8^  " 

Including  30  feet  of  steam-hose  and  couplings. 


CHAPTER  IV. 


FRAMED  BENTS. 

FRAMED  BENTS  are  built  upon  a  foundation  of  some  kind,  the  object  of  which  is  to  raise 
the  sill  from  the  ground  and  thus  lengthen  its  life — which  at  the  best  is  short  enough — as 
much  as  possible.  When  the  sill  is  partly  or  wholly  buried  in  the  ground  decay  soon  sets  in 
and  proceeds  with  great  rapidity,  and  the  practice  either  of  allowing  the  sill  to  rest  upon 
the  ground  or  of  partially  or  wholly  covering  it  with  earth  is  to  be  very  strongly  condemned. 

The  foundations  maybe  divided  into  seven  classes:  masonry,  pile,  mud-sill  or  sub-sill, 
grillage,  crib,  solid  rock,  and  loose  rock. 

Masonry  foundations  are  of  third-class  masonry,  and  are  built  of  such  material  as  may  be 
found  near  at  hand.  The  stones  should  be  as  large  and  flat  as  possible,  all  those  with  any 
rounded  surfaces  being  carefully  excluded.  The  masonry  should  penetrate  the  ground  to 
below  the  frost-line  so  as  to  prevent  heaving,  which  would  tend  to  rapid  disintegration  and 
destruction.  It  should  also  rest  upon  a  firm  bed.  For  low  trestles,  where  the  sills  are  short, 
the  masonry  may  extend  the  whole  length  of  the  sill,  but  where  the  bents  are  over  10  ft.  in 
height  it  becomes  more  economical  to  divide  it  into  three  sections,  placing  one  part  under 
the  centre-posts  and  one  under  either  batter-post.  The  part  under  the  centre-posts  should 
be  long  enough  to  give  a  good  solid  bearing  to  each  of  them,  and  to  extend  some  little  dis- 
tance beyond  them.  The  faces  of  the  foundation  should  have  a  slight  batter,  thus  giving  it. 
the  shape  of  a  truncated  pyramid.  Figs.  38  and  39  show  the  shape,  size,  and  arrangement  of 
the  masonry  foundations  as  used  on  the  New  York,  Ontario  &  Western  Railroad. 


FIG.  38. 


FIG.  39. 


MASONRY  FOOTINGS. 


Masonry  forms  excellent  foundations — more  durable  than  any  other  kind.  They  are 
practically  indestructible  if  well  built,  not  being  liable  to  decay,  and  are  very  economical  in 
maintenance,  as  the  life  of  the  sills  is  greatly  prolonged,  and  the  repairs  to  the  foundation 
amount  to  practically  nothing.  It  is  well  (but  hardly  the  general  rule)  to  fasten  the  sills  to 
the  foundations  by  means  of  iron  rods  built  into  the  masonry.  This  prevents  vibration  to  a 
very  considerable  extent. 

These  rods  should  be  from  £  in.  to  I  in.  in  diameter  and  about  3  ft.  long.  If  desired,  a  head 
may  be  formed  on  the  lower  end  and  anchor-plates  employed,  though  this  is  not  essential. 

In  pile-foundations  one  pile  is  usually  placed  under  each  post.     The  sill  is  fastened  to 

24 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


the  piles  in  any  of  the  ways  previously  described  for  fastening  on  the  caps  of  pile-bents.  In 
very  high  trestles  it  is  at  times  found  desirable  to  place  two  piles  under  each  post.  It  is 
often  convenient,  especially  where  pile-timber  is  plenty,  and  desirable  framing  timber  of  a 
considerable  length  is  difficult  to  obtain,  to  use  a  pile-bent  of  from  10  to  20  feet  high,  and 
then  place  a  framed  one  on  top  of  it.  On  some  roads  when  the  trestle  is  over  a  water-way, 
a  pile-foundation  is  surmounted  by  a  framed  bent,  £he  piles  being  of  such  a  height  as  to 
always  remain  entirely  submerged.  By  this  means  tfhe  decay  due  to  the  alternate  wetting 
and  drying  of  the  timber  is  almost  wholly  confined  to  the  framed  portion,  which  is  easily 
replaced :  hence  it  is  said  that  this  style  of  structure  is  very  economical  over  bays  and  inlets 
affected  by  the  tides. 

The  practice  as  to  mud-sills  or  sub-sills  varies  a  great  deal.  Some  prefer  thin  planks 
only  3  in.  or  4  in.  thick;  others,  material  12  in.  by  12  in.  The  thicker  material  is  the 
better,  as  it  raises  the  sill  higher  from  the  ground,  and  is  not  so  rapidly  weakened  by  decay. 
Sub-sills  should  only  be  used  when  the  surface  is  rock  or  where  the  ground  is  quite  hard.  In 


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V 

—  ' 

FIG.  40. — GRILLAGE  FOUNDATION. 

other  cases  piles  or  masonry  should  be  employed,  depending  on  circumstances.  Some  go  to 
the  trouble  of  notching  the  sub-sill  and  sill  together.  This  is  not  necessary,  and  adds  more  to 
the  expense  of  construction  than  the  good  derived  from  it  warrants.  It  is  always  better  to 
spike  or  drift-bolt  the  two  together  to -some  extent,  though  it  is  not  necessary  to  fasten  every 
sub-sill  in  this  way  when  there  are  more  than  four  under  the  bent.  When  longitudinal  girts 
are  placed  immediately  above  the  sill,  no  fastening  at  all  of  the  sill  to  the  sub-sill  is  required. 
A  grillage  was  used  as  a  foundation  for  a  trestle  on  a  branch  of  the  New  York,  New 
Haven  &  Hartford  Railroad,  over  Hanover  Pond,  at  Meriden,  Conn.  The  water  was  still 


26  A    TREATISE  ON   WOODEN   TRESTLE  BRIDGES. 

and  shallow,  and  the  bottom  soft,  treacherous,  and  of  unknown  depth.  Piles  could  not  be 
economically  used,  and  hence  Mr.  J.  Devin  devised  this  expedient. 

The  grillage  was  made  by  arranging  a  number  of  railroad  ties  about  15  in.  apart,  as 
shown  in  Fig.  40,  and  fastening  them  together  by  two  3  in.  by  10  in.  binder-planks  spiked 
to  each  tie.  It  was  then  floated  to  its  place  and  a  framed  bent  placed  upon  it,  one  grating 
being  used  for  each  bent.  The  weight  of  the  structure  sunk  the  grillages  so  that  they  rested 
on  the  bottom.  The  sills  were  not  fastened  to  them,  the  bents  being  kept  in  place  by  both 
sway  and  longitudinal  bracing.  It  seems  as  though  it  might  be  more  advisable  ordinarily  to 
fasten  the  sills  to  the  foundation  by  a  few  drift-bolts.  This  foundation  is  said  to  give  perfect 
satisfaction  under  constant  traffic.  One  grating  was  put  in  with  the  binder-planks  under- 
neath, but  was  quickly  undermined  its  whole  length  either  by  a  slight  current  or  by  springs. 
The  trouble  was  obviated  by  turning  the  grating  over.* 

On  some  of  the  branches  from  the  Cripple  Creek  extension  of  the  Norfolk  &  Western 
Railroad,  crib  foundations  are  used  for  the  trestles.  These  cribs  are  formed  by  piling  logs  on 
top  of  each  other,  notching  them  where  they  cross,  and  then  filling  up  the  interior  with  stones 
(Fig.  41). 


FIG.  41. — CRIB  FOUNDATIONS. 


They  are  built  pyramidal  in  form,  and  are  suitable  for  side-hill  work  where  the  slope  is 
not  too  great,  though  their  use  is  not  by  any  means  limited  to  this  kind  of  ground,  as  they 
form  as  good  a  foundation  on  the  level.  When  on  a  side-hill  the  ground  beneath  them  is 
excavated  in  steps,  and  the  cribs  are  built  up  level  so  as  not  to  necessitate  the  breaking  of  the 
sill.  The  logs  composing  the  crib  should  be  at  least  10  in.  in  diameter  at  the  smallest  place, 
and  it  is  better  if  they  are  not  under  a  foot. 

A  novel  plan  for  obtaining  a  foundation  on  a  side-hill  where  the  surface  was  of  solid  rock 
was  adopted  on  some  work  by  Mr.  J.  E.  Woods,  C.E.  Holes  were  cut  in  the  rock  where 
the  feet  of  the  posts  were  to  come,  and  after  the  posts  were  placed  in  them  and  the  bent 

*  Eng.  and  Build.  Rec.,  Dec.  24.  1887. 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


27 


completed,  the  remaining  spaces  were  filled  with  cement  (Fig.  42).  Of  course  no  sills  are 
required  with  this  form  of  foundation.  The  ends  of  all  the  posts  were  tarred  before  they  were 
placed  in  the  holes. 

Where  loose  rock  is  plentiful,  and  cement  or  lime  costly,  pretty  serviceable  foundations 
may  be  obtained  by  filling  trenches  with  it.  Sub-sills  should  be  laid  on  top  of  these,  and  the 
sills  rest  upon  them.  This  is  done  in  order  to  distribute  the  weight  over  a  larger  surface. 

The  life  of  sub-sills  can  often  be  greatly  lengthened,  and  loose  rock  foundations  kept 


FIG.  42. — SOLID  ROCK  FOUNDATIONS  ON  SIDE-HILL. 

quite  dry,  by  digging  a  trench  entirely  around  them,  several  feet  away,  and  leading  off  the 
water  that  accumulates. 

Sills  (except  when  split)  should  not  be  of  smaller  timber  than  12  in.  square,  and  should 
extend  from  12  in.  to  18  in.  beyond  the  outside  of  the  batter-posts.  In  very  high  trestles 
the  sills  are  usually  made  up  of  several  pieces.  Some  examples  of  these  are  shown  in  the 
cuts  of  special  trestles.  When  the  sills  are  mortised,  a  drip-hole 
^  in.  in  diameter  should  always  be  bored  with  a  downward 
inclination  from  the  bottom  of  the  mortise  to  the  outside  of  the 
sill.  Figs.  43  and  44  show  the  method  of  boring  these  drips  on 
two  roads.*  The  object  is  to  keep  the  water  from  collecting  in 
the  mortises,  which  would  hasten  the  decay  of  the  sill. 


FIG.  43. 


FIG.  44. 


DRIP-HOLES. 


*  Charleston,  Cincinnati  &  Chicago  Railroad  ;  Central  Railroad  of  Georgia,  V.  H.  Kriegshaber,  Assistant 
Engineer. 


28 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


There  are  usually  four  posts  to  a  bent — two  vertical  or  plumb  posts,  and  two  batter-posts. 
As  a  rule,  they  are  all  made  of  the  same  size  timber, — 12  in.  X  12  in.  Occasionally  either 
all,  or  else  the  batter-posts,  are  made  of  9-in.  X  12-in.  or  lo-in.  X  12-in.  material,  and  some- 
times, in  very  low  trestles,  lo-in.  X  io-in.  is  employed. 

The  large  size,  12-in.  X  12-in.,  is  rather  to  be  preferred  in  all  cases,  it  being  far  more 
advisable  to  have  an  excess  of  strength  in  this  part  than  any  tendency  to  weakness.  The 
extra  cost  for  timber  does  not  amount  to  very  much.  The  plumb-posts  should  be  spaced 
from  4  ft.  to  5  ft.  between  centres,  and  the  batter  posts  u  ft.  from  centre  to  centre  at  the 
top,  immediately  under  the  cap.  The  inclined  posts  should  have  a  batter  of  3  in.  per  foot. 
This  give  a  broad  base,  and  adds  considerably  to  the  stiffness  of  the  bent.  Other  batters  are 
frequently  made  use  of,  varying  from  2  in.  to  4  in.  per  foot,  though  2%  in.  and  3  in.  are  the 
most  common.  Table  VIII  gives  the  length  of  the  batter-posts  for  different  heights  at  an 
inclination  of  3  inches  per  foot. 

TABLE  VIII. 

Length  of  Batter-posts ;  Batter  3"  per  Foot. 


s 

Length  of  Stick. 

s' 

Length  of  Stick. 

=• 

Length  of  Stick. 

s 

Length  of  Stick. 

3  §t  e 

u     Z 

JS 
.t!  u    . 

£ 

i§" 

5  s  « 

U         u 

£ 

u  u^ 

3  fe  c 

S3    Si 

a 

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0   ^^ 

5  S  e 

S3     53    1  -5  „  . 

•-  u  rt 

~    3 

-,    •_     X 

?  cs-o 

£•  V>  S 

!/:  £  rt 

2     2 

%  rt-o 

•5  "u->C 

^M  w  rt 

•o     -a 

•2  Vic 

''£  rt  m 

•£  Vic 

Q  .0  5" 

3^3 

Jd  3  C 

S  ^  c 

Q  ^  O« 

3  O  y 

•u  oJ 

^   O   £• 

P'  n   Q. 

3  2  "3 

^£  3  C 

^  ^  c 

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3  2  "3 

^  3  c 

"  o  2 

U 

O        o 

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J3       ^3 

.y^w 

^  S  5 

I/)      t/5 

</5 

w    (/j 

(7) 

55 

w 

"H 

ft.    in. 

ft.      in. 

ft.      in. 

ft.      in. 

ft.    in. 

ft.       in. 

ft.       in. 

ft.       in. 

ft.     in. 

ft.       in. 

ft.      in. 

ft.       in. 

ft.    in. 

ft.    in. 

ft.       in. 

ft.       in. 

3    o 

3    i 

3     4 

4      2 

13 

13      41 

13     71 

H  sf: 

23 

23    8t 

23  H| 

24    9i 

33 

34  ot 

34     3i 

35     ii 

3    6 

3    7t 

3  lot 

4    8£ 

13     6 

13    II 

14      2 

IS 

23     6 

24     2f 

24    Sf 

25     3f 

33     6 

34  6f 

34    9t 

35     7| 

4 

4    it 

4    4t 

5    2| 

H 

H     5t 

14    8t 

15    6t 

24 

24    8f 

24  III 

25     9l 

34 

35  o| 

35     3s 

4    6 

4    7f 

4  iof 

5    8f 

14    6 

14  1  if 

IS       2f 

16    of 

24    6 

25    3 

25'  6 

26     4 

34     6    35  6f 

35     9* 

36    7! 

5 

5    il 

5    41 

6     2f 

15 

15    51 

15     8i 

1  6    64 

25 

25    9i 

26    oj 

26   10^ 

35          36  of 

36     31 

37     il 

5    6 

5    8 

5   !  r 

6      9 

15     6 

15  iif 

16     2f 

17    of 

25     6 

26    3! 

26    6f 

27     4t 

35     6    36  7^36  ioi 

37     8t 

6 

6     2t 

6    Si 

7    3i 

16 

16    51 

16     8f 

17    61 

26 

26    9^27    of 

27   iof 

36 

37  it  37    4i 

38     2t 

6    6 

6    8f 

6  iif 

7    9t 

16    6 

17    o 

17     3 

18    i 

26     6 

27    3^27    6* 

28     4f 

36     6 

37  7i37  ioi 

38     8i 

7 

7    2£ 

7    Si 

8    3i 

17 

17     6J 

17     9i 

18    -]\ 

27 

27  10    28     i 

28   u 

37 

38  if  38    4f 

39     2f 

7     6 

7    8* 

7  u* 

8    9* 

17     6 

18    (4 

18     3£ 

19    ii 

27     6 

28    4^  28    7^ 

29     51 

37     6 

38  71 

38  iof 

39     8f 

8 

8    3 

8    6 

9    4 

18 

18     6f 

18     9f 

19    7f 

28 

28  iof  29     if 

29  iif 

38 

39  2 

39     5 

40     3 

8    6 

8    9t 

9    of 

9  lot 

18    6 

19     of 

19     3l 

20    if 

28     6 

29    4t 

29    71 

30   si 

38     6 

39  Si 

39  ni  40    9i 

9 

9    3t 

9    6f 

10    4f 

19 

19     7 

19  10 

20      8 

29 

29  iof  30    if 

30  i  if 

39 

40  2-240     5-8- 

41     3t 

9    6 

9    9t 

10     Oi 

10  io£ 

19    6 

20     i\ 

20     4} 

21      2\ 

29     6 

30    4l 

30    71 

3i     51 

39    6 

40  8f  40  n|  41     9f 

10 

10    3f 

10    6f 

u    4f 

20 

20    7! 

20    I0f 

21      8f 

30 

30  ii 

31      2 

32     o 

40 

41  2f4i     5f  42     3f 

10    6 

10    9! 

II      Of 

II    iof 

20      6 

21        l| 

21     4t 

22     2^ 

30    6 

3i     Si 

31     8^ 

32     6| 

40    6 

41  9 

42    o   42  10 

1  1 

u    4 

u    7 

12    5 

21 

21       7f 

21     lOf 

22      8$ 

3r 

3'  i  it  32    2J 

33    °i 

41 

42  3t 

42     6t  43     4i 

u     6 

II    IOJ 

12      1^ 

12   IlJ 

21       6 

22       if 

22      41 

23      2f 

31     6 

32    sf  32    8f 

33     6f 

41     6 

42  9143    of  43  iof 

12 

12    4^ 

12     7i 

13    Si 

22 

22      St 

22    II-jj 

23    9i 

32 

32  nl 

33    2f 

34    of 

42 

43  31 

43    6^44    4^ 

12      6 

12  lof 

13     If 

13  Hf 

22      6 

22       2j 

23      St 

24    3i 

326 

33    6 

33    9 

34     7 

42     6 

43  9* 

44    of 

44  iof 

The  second  columns  in  the  table  give  the  length  of  the  post  without  tenons,  measuring 
along  one  of  the  faces  after  the  ends  have  been  cut  off  at  the  proper  angle ;  the  third  columns, 
the  length  of  a  piece  of  timber  with  square  ends  required  to  cut  the  post;  and  the  fourth 
columns,  the  length  of  a  piece  of  timber  with  square  ends  required  when  there  is  a  tenon  5 
inches  long  on  each  end.  The  table  is  used  thus :  What  is  the  length  of  timber  required  for 
the  batter-posts  of  a  bent  21  ft.  6  in.  high,  the  posts  being  connected  to  both  cap  and 
sill  by  a  5-inch  tenon?  Taking  the  thickness  of  both  cap  and  sill  from  the  height  of  the 
bent  in  order  to  find  the  distance  between  them,  we  have  21  ft.  6  in.  —  2  ft.  =  19  ft.  6  in. 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


29 


Now  looking  in  the  table  we  find  in  the  fourth  column,  opposite  19  ft.  6  in.,  that  the  length 
required  is  21  ft.  2\  in. 

For  framing  in  the  field,  try-squares,  set  to  the  proper  angle  for  cutting  the  ends  of 
the  batter-posts,  are  very  convenient.  Fig.  45  shows  a  form  of  template  for  direct  use.  It 
consists  of  a  £-in.  board  cut  to  the  requisite  angle  with  a  I  J-in.  square  piece  fastened  along 
one  edge.  It  is  used  in  the  same  manner  as  an  ordinary  carpenter's  square. 

Some  designers  prefer  to  have  the  batter-posts  touch  the  plumb-posts  where  they  meet 
the  cap,  as  in  Fig.  46,  while  others  incline  all  of  the  posts  (Fig.  47).  When  all  of  the  posts  are 


L 


FIG.  46. 


FIG.  45. 
BATTER-POST  TEMPLATE. 


FIG.  47. 
ARRANGEMENT  OF  POSTS. 


inclined,  the  distance  between  them  at  the  top  is  fixed,  as  is  also  the  batter  of  the  outer  posts, 
while  that  of  the  inner  ones  varies  with  the  height. 

It  is  well  to  make  solid  caps  of  at  least  12  in.  X  12  in.  timber  and  14  ft.  long.  Where 
the  timber  is  inclined  to  be  weak  or  brittle,  they  should  be  12  in.  wide  by  14  in.  deep. 
There  are  six  different  ways  of  joining  the  sills,  posts,  and  caps  together,  viz.,  by 

Mortise  and  tenon  ;  Dowels  ;  Iron-joint  plates  ; 

Drift-bolts ;  Plasters ;  Split  caps  and  sills. 

A  tenon  3  in.  thick,  8  in.  wide,  and  5  in.  long  is  a  very  good  size.  The  mortise  should 
be  a  little  deeper — say  ^  in. — than  the  length  of  the  tenon.  They  should  be  snugly  fitted  to 


L 


FlG.  48. — ARRAN9EMENT   OF    DRIFT-BOLTS. 


FIG.  49. — ARRANGEMENT  OF  DOWELS. 


each  other,  and  the  sides  made  as  smooth  as  practicable.     The  same  precaution  in  regard  to 
boring  the  holes  in  the  tenons,  as  mentioned  when  speaking  of  the  tenons  on  piles,  should  be 


3o  A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 

observed  here,  so  that  the  work  may  be  drawn  tightly  together.     Wooden  pins  should  always 

be  used  to  hold  the  parts  together. 

When  drift-bolts  are  employed,  two  should  be  used  for  fastening  each  post  to  the  sill,  and 

one  for  securing  it  to  the  cap.     A  hole  very  nearly  the  size  of  the  drift-bolt  should  be  bored 

through  the  first  stick  of  timber  penetrated,  and  one  somewhat  smaller  through  the  balance. 

The  drift-bolts  may  be  arranged  as  in  Fig.  48. 

In  dowel-joints  two  dowels  should  be  used  in  both  cap  and  sill  to  each  post.    They  should 

be  f  in.  in  diameter,  by  at  least  8  in.  long,  and  arranged  as  in  Fig.  49. 

A  plaster-joint  is  one  of  the  most  convenient  forms  for  some  uses.  It  is  especially  advan- 
tageous when  making  repairs,  and  is  made  by  spiking 
and  bolting  a  piece  of  plank  3  in.  thick,  12  in.  wide,  and 
3  ft.  long  to  each  side  of  the  cap  or  sill,  as  the  case  may 
be,  and  to  each  post.  This  joint  has  been  adopted  by 
the  Delaware  and  Hudson  Canal  Co.,  and  is  said  to  be 
proving  very  satisfactory.  The  details  are  shown  in 
Fig.  50.  With  this  joint  all  the  posts  should  be  notched 


FIG.  50.-PLASTER-JOINTS.  J,    .^ 

There  is  a  joint  in  use  on  the  New  York,  Lake  Erie  &  Western  Railroad,*  made  with  an 
iron  plate  bent  in  a  special  manner,  and  which 
allows  of  the  very  easy  removal  of  parts  for 
repairs,  while  at  the  same  time  it  is  strong  and 
efficient.  Fig.  51  shows  this  joint  in  all  its 
details.f 

Nearly  every  conceivable  combination  of 
the  above  joints  with  or  without  notching  is 
in  use.  For  batter-posts,  the  notch  shown  in 
Fig.  52  is  rather  better  than  that  in  Fig.  53. 

The  height  of  the  bent  is  measured  from 
the  under  side  of  the  sill  to  the  top  of  the  cap. 


\L ' 

FIG.  51.— IRON  JOINT-PLATE,  N.Y.,  L.  E.  &  W.  R.  R. 


FIG.  52.  FIG.  53. 

BATTER-POST  NOTCHES. 


The  distance  between  the  cap  and  sill  should 
not  be  quoted  as  its  height,  as  is  frequently,  though  wrongly, 
done. 

Bents  should  be  spaced  at  such  a  distance  between  centres 
as  will  use  the  length  of  timber  easiest  to  obtain  for  stringers  in 
the  most  economical  manner.  The  distance  varies  from  12  ft.  to  16  ft.;  spans  of  14  ft.  and 
15  ft.  being  the  most  general.  Where  it  is  possible,  all  the  bents  should  be  evenly  spaced, 
only  employing  spans  of  unequal  length  where  they  cannot  be  avoided. 

That  which  was  said  in  the  chapter  on  Pile-bents  in  relation  to  split-caps  applies  with  the 
same  force  to  framed  bents. 

Both  the  sills  and  caps  on  the  Savannah,  Florida  &  Western  Railroad,  W.  B.  W.  Howe,  Jr., 
Chief  Engineer,  are  split  horizontally,  the  upper  and  lower  pieces  being  held  together,  and 
kept  from  sliding  by  pins  driven  into  holes  bored  through  them. 


*  Also  used  on  the  Chicago,  Rock  Island  &  Pacific  Railroad, 
t  Engineering  News,  Nov.  5,  1887. 


CHAPTER  V. 
FLOOR   SYSTEM. 


Corbels. — Corbels  are  pieces  of  timber  placed  lengthwise  of  the  stringers,  between  them 
and  the  caps.  They  are  usually  from  4  ft.  to  8  ft.  long,  extending  equal  distances  on  either 
side  of  the  centre  of  the  cap.  They  are  not  much  in  favor,  for  good  reasons.  To  a  certain 


i 


p 


FIG.  54.— DELAWARE  &  HUDSON  CANAL  Co. 

rffi 


j 


FIG.  56. — LOUISVILLE  &  NASHVILLE  R.  R. 


FIG.  58. — OHIO  CONNECTING  R.  R. 


it»  li:»  .t! 


2tJ- 


FIG.  60.  —  CHICAGO  &  NORTHWESTERN  R.  R. 


*. 


FIG.  55. — CHARLESTON,  CINCINNATI  &  CHICAGO  R.  R. 


I 

^ 

I 

1 

t 

1 

s 

Ii 

1 

i 
i 

r 

I 

£ 

? 

1 

J" 

* 

V 

J 

FIG.  57. — SCIOTO  VALLEY  R.  R. 


'unr 

flu 

%. 

t  I  \'V 

j 

< 

»|o  |           f     / 

It  —  J 

^  .  u 

!         ) 

! 
* 

i 

^     tt  •> 

•V 

V 

FIG.  59. — NEW  YORK,  LAKE  ERIE  &  WESTERN  R.  R. 


FIG.  61.  —  NEW  YORK,  WOODHAVEN  &  ROCKAWAY  R.  R. 


FIGS    54  TO  61.—  DETAILS  OF  CORBELS. 

extent  they  are  very  useful,  but  they  also  have  many  disadvantages.  They  give  extra  support 
to  and  consequently  strengthen  the  stringers  ;  but  for  various  reasons,  as  the  stringers  should 
not  be  made  lighter  on  this  account,  this  does  not  count  for  much.  They  also  add  stiffness 

31 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


to  the  stringer-joint,  but  sufficient  stiffness  for  all  intents  and  purposes  may  be  obtained  from 
a  well-designed  joint  without  them.  They  add  to  the  cost,  not  only  in  labor  and  lumber,  but 
also  require  the  use  of  a  considerably  larger  amount  of  iron.  They  increase  the  number  of 
joints,  and  hence  the  places  for  the  lodgment  and  beginning  of  decay.  If,  however,  it  is 
thought  desirable  to  use  them,  the  different  ways  of  fastening  the  stringers  to  them,  and  they 
in  turn  to  the  caps,  may  be  seen  in  Figs.  54  to  61. 

Corbels  should  be  notched  down  about  I  in.  over  the  cap.  A  peculiar  and  rather  com- 
mendable method  of  separating  the  corbels  and  stringers  from  each  other  by  cast-iron  blocks, 
as  adopted  on  the  Chicago  &  Northwestern  Railroad,  is  shown  in  Fig.  60. 

Stringers. — A  stringer  should  be  placed  immediately  beneath  each  rail,  and  in  order  to 
guard  against  defective  timber  it  ought  to  be  "split"  or  composed  of  two  or  more  pieces. 
These  pieces  should  be  separated  from  each  other  by  either  cast-iron  washers  or  spools,  or 
wooden  packing-blocks,  or  both.  A  considerable  difference  exists  in  the  present  practice 
as  to  the  amount  of  separation.  It  varies  all  the  way  from  nothing  to  13  in.  From  i£  in.  to 
2  in.  is  a  very  good  distance.  In  Figs.  62  to  72  are  shown  a  number  of  cast-iron  separators, 
and  in  Figs.  73  to  82  a  number  of  wooden  packing-blocks.  Among  the  latter,  those  having 
the  general  form  of  Fig.  75  are  to  be  preferred.  These  are  to  be  placed  immediately  above 
the  caps.  Those  packing-blocks  which  are  notched  are  of  course  placed  so  that.the  cap  fits 


FIG.  62. 


FIGS.  63,  64. 


FIG.  65. 


FIG.  66. 


FIG.  67. 


FIG.  68 


FIG.  70. 


o 

.«•> 

FIG.  71 


FIG.  72. 


SCALE  ,,„„„„, 

2"  3"  4"  B"  e"  7    s"  9    ip  i  i*ia 

.     i     i     i     i    i     '     ' i     i     i 


FIGS.  62  TO  72.— CAST-IRON  SEPARATORS. 


FIG.  73 


FIG.  74. 


FIG.  75. 


FIG.  77- 


e 


FIG.  78. 


FIG.  79. 


FIG.  80. 


FIG.  8 1. 


FIG.  76. 


FIG.  82 


7     8     9     1|0 


FIGS.  73  TO  82.—  WOODEN  PACKING-BLOCKS. 

into  the  notch.  Frequently  the  packing-blocks  made  of  the  heavier  material  are  used  merely 
as  splice-blocks,  they  being  separated  from  the  stringers  by  thin  cast-iron  separators,  such  as  is 
shown  in  Fig.  67.  Many  fasten  the  stringers  together  by  intermediate  bolts  placed  either  at 
the  centre  of  the  span  or  at  regular  intervals  along  it.  Separators  or  packing-blocks  are  of 
course  required  to  be  placed  between  the  stringers  wherever  these  bolts  are  located.  With 
good  timber  and  spans  of  12  ft.  to  14  ft.  these  intermediate  bolts  are  not  necessary,  and  may 
be  just  as  well  omitted  as  not. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


33 


When  it  is  possible,  the  stringer-pieces  should  be  long  enough  to  extend  over  two  spans 
and  the  joints  broken.  Various  styles  of  stringer-joints  and  ways  of  arranging  intermediate 
bolts  are  shown  in  Figs.  83  to  98.  The  arrangement  shown  in  Fig.  83  is  to  be  greatly  pre- 


S 


ur 


FIG.  83.— PENNSYLVANIA  R.  R.        FIG.  84.— WISCONSIN  CENTRAL  R.  R.          FIG.  85.— N.  Y.,  P.  &  B.  R.  R. 


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FIG.  86.  — B.  &  M.  R.  R.  IN  NEB. 


FIG.  87.— A.  &  P.  R.  R. 


FIG.  88. — GEORGIA  PACIFIC  RY. 


3        £- 


ur 

FIG.  89.— C.,  N.  O.  &  T.  P.  RY.  FIG.  90.— CENTRAL  R.  R.  OF  GA.       FIG.  91.— GULF,  COL.  &  SANTA  FfiR.R 


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FIG.  92. — D.,  T.  &  FT.  WORTH  R.  R,     FIG.  93. — CHICAGO  &  W.  MICH.  Rv.       FIG.  94. — CHICAGO  &  ATLANTIC  RY. 


. 

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FIG.  95.— B.;  C.  R.  &  NORTHERN  R.R.    FIG.  96.— SAN  F.  &  N.  PACIFIC  R.  R.       FIG.  97.— ST.  P.,  MIN  #  M.  RY. 


FIG.  98. — OREGON  PACIFIC  R.  R. 
FIGS.  83  TO  98.— DETAILS  OF  STRINGER-JOINTS. 


34 


A    TREATISE-  ON    WOODEN   TRESTLE  BRIDGES. 


ferred,  because,  should  the  support  for  any  reason  become  weakened,  the  joint,  when  it  settles 
as  a  weight  comes  upon  it,  closes  at  the  top  and  tends  to  open  at  the  bottom.  Now  the 
lower  bolts  act  somewhat  as  a  fulcrum,  and  the  effect  will  be  to  tend  toward  splitting  the 
stringer  from  these  bolts  to  the  nearest  end.  As  this  arrangement  gives  the  most  material 
where  there  is  the  greatest  liability  to  split,  and  consequently  at  the  weakest  point,  it  forms 
the  strongest  kind  of  a  joint. 

Such  joints  as  those  shown  in  Figs.  91,  97,  and  98  cannot  be  condemned  too  strongly,  and 
are  always  to  be  avoided.  Those  illustrated  in  Figs.  87,  88,  89,  90,  92,  93,  94,  and  96  are 
also  poor  on  account  of  the  packing-bolts  being  so  close  to  the  end  of  broken  stringer-pieces, 
and  also,  in  some  cases,  on  account  of  there  being  too  few  of  them.  That  in  Fig.  92  would  be 
an  excellent  joint  were  the  lower  bolts  placed  a  foot  or  so  farther  apart.  The  joint  shown  in 
Fig.  86  is  said  by  Mr.  I.  S.  P.  Weeks,  Chief  Engineer  C.,  B.  &  Q.  R.  R.  west  of  the  Missouri 
River,  to  have  proved  very  efficient.  It  has  carried  an  engine  over  after  the  bent  has  been 
washed  out. 

The  bolts  holding  the  stringer-pieces  together,  and  which  are  called  packing-bolts,  should 
be  long  enough  to  extend  clear  through  from  face  to  face  of  the  complete  stringer,  and  allow 
of  placing  a  cast-iron  washer  under  both  nut  and  head. 

When  the  stringers  are  not  fastened  directly  to  the  caps  they  should  be  notched  over 

r — — j          them   I  in.     A  method  for  holding  the  stringers  in  place,  and 

f=±M^^MM±=±^^^^S^::±|      which  is  becoming  quite  general,  is  shown  in  Fig.  99.     It  con- 
I~J  \  \         sists  of  a  piece  of  3  in.  X  12  in.  plank,  fastened,  outside  of  each 

II         LV  1/v-J         \j*        stringer,  to  the  cap  by  four  log-screws  or  by  spikes.      The 

stringers  in  their  turn  are  kept  at  the  proper  distance  apart 
either  by  a  spreader  made  of  the  same  material  or  by  fasten- 
ing the  ties  to  them. 

The  size  of  the  stringer-pieces  in  cross-section  will  vary 
with  the  span,  variety  of  timber,  and  weight  of  the  traffic. 


U 

FIG.  99. — STRINGER  FASTENING. 


They  should  be  of  sufficient  dimensions  to  prevent  any  considerable  deflection  by  a  passing 
train.  For  long  spans,  or  on  lines  having  heavy  loads  and  engines,  each  stringer  should  be 
composed  of  three  pieces ;  in  other  cases  two  are  sufficient.  The  practice  of  the  Pennsyl- 
vania Railroad  in  this  respect  is  given  in  Table  IX. 

TABLE  IX. 

Trestle-stringers,    Pennsylvania   Railroad   Standard. 


Dimensions  of  Stringers. 

Clear  Span. 

Number  of  Pieces 
under  each  Rail. 

Width  of  each 
Piece. 

Depth  of 
Stringers. 

10  ft. 
12    " 

2 
2 

8  in. 

8    " 

15  in. 

16    " 

14    " 

16   " 

2 
3 

IO     " 

8    " 

17    " 
17    " 

A  "  jack-stringer,"  composed  of  a  single  piece,  should  always  be  placed  under  either  end 
of  the  ties,  as  in   Fig.  99.     By  such  an  arrangement  many  advantages  are  secured.     The 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


35 


principal  one  is  in  case  of  a  derailment,  when,  if  the  ties  give  way,  the  cars  are  not  liable  to 
fall  to  the  ground  as  they  otherwise  might.  As  the  ends  of  the  ties  are  supported,  the 
chances  are  very  much  in  favor  of  their  not  being  broken  in  such  a  case.  Thus  the  factor  of 
safety  is  largely  increased.  These  outer  stringers  should  be  long  enough  to  extend  over  two 
spans,  and  should  always  be  securely  fastened  to  the  caps  by  a  drift-bolt  through  either  end 
and  the  centre. 

The  ends  of  the  stringer-pieces  are  generally  butted  together.  There  are  two  excep- 
tions to  this  otherwise  universal  rule:  in  the  trestles  on  the  San  Francisco  &  North  Pacific 
Railway,  Fig.  96,  the  ends  are  separated  |  in.,  and  in  those  of  the  Chicago  &  Northwestern 
Railroad,  Fig.  60,  they  are  bevelled  I  in. 

Several  roads  have  adopted  the  policy  of  trussing  stringers  having  a  span  of  14  ft.  or 
over  after  they  become  three  or  four  years  old.  This  end  is  accomplished  on  the  Pontiac, 
Oxford  &  Port  Austin  Railroad,  Geo.  A.  Nettleton,  Chief  Engineer,  by  arranging  an  iron  rod 
and  pieces  of  rail  as  shown  in  Fig.  100.  While  this  treatment  has  a  very  beneficial  effect  in 
some  respects,  and  adds  considerably  to  the  strength  of , 
the  structure,  still  it  seems  as  though  the  men  in  charge 
of  the  trestles,  as  well  as  the  inspectors,  would  be  FlG"  IOO--TRUSSING  STRINGERS. 

tempted  to  rely  too  much  upon  this  extra  strength,  and  allow  timber  to  remain  in  service 
which  should  for  safety  have  been  removed  long  before.  The  carelessness  which  would 
thus  tend  to  be  inculcated,  would  prove  very  dangerous  on  the  majority  of  roads. 

Ties. — Ties  may  be  of  6-in.  X  8-in.  timber,  sawed,  and  should  have  a  length  of  12  ft. 
They  should  be  notched  over  the  stringers  I  in.,  and  if  outside  stringers  are  used  with  notched 
guard-rails  they  need  not  be  otherwise  fastened.  In  other  cases  they  should  be  spiked  to 
the  stringers.  There  are  many  different  ways  of  arranging  the  spikes.  Some  fasten  every 
third  or  fourth  tie  only,  while  others  spike  every  tie.  It  is  always  better  to  stagger  the  spikes 
or  arrange  them  zigzag,  as  in  Fig.  101.  Figs.  101  to  109  show  several  of  the  different 
ways  of  arranging  these  fastenings.  Opinions  as  to  the  spacing  of  the  ties  vary.  They 
are  placed  anywhere  from  12  in.  to  24  in.  from  centre  to  centre.  The  closer  together 
they  are  put  the  better;  they  should  never  be  spaced  with  centres  over  12  in.  apart,  leaving 
6-in.  openings  between  the  ties;  9-in.  centres  are  far  better  even  than  12-in.  On  the  West 
Shore  Railroad  small  blocks  4  in.  thick  X  8  in.  square  are  spiked  to  the  stringers  between  the 
ties  in  such  a  manner  as  to  act  as  a  cover  for  the  space  between  the  stringer-pieces  (Fig.  101). 
While  these  blocks  serve  a  good  end  by  preventing  "bunching,"  and  in  keeping  out  the  rain 
and  moisture,  they  are  hardly  advisable  because  of  their  interfering  with  the  free  circulation 
of  the  air  between  the  separate  pieces  of  the  stringer,  as  well  as  on  account  of  their  preventing 
the  penetration  of  the  sunlight  into  these  places. 

Often  when  the  ties  are  not  notched,  and  it  is  desired  to  use  some  other  form  of  fasten- 
ing than  spiking,  dowel-pins,  made  of  f-in.  iron  5  in.  long,  may  be  resorted  to.  They  may  be 
arranged  as  in  Fig.  109. 

Guard-rails. — Guard-rails  serve  two  principal  purposes :  first,  to  keep  the  train  from 
leaving  the  bridge  in  case  of  a  derailment ;  and  second,  to  aid  in  keeping  the  ties  in  their 
proper  places,  and  give  stiffness  to  the  floor  system.  They  should  always  be  employed,  and 
where  an  outside  stringer  is  used  should  be  placed  immediately  above  it.  They  need  not  be 


36  A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 

made  of  very  heavy  timber,  nor  should  they  be  too  light;  6  in.  X  8  in.,  with  the  narrow  face 
down,  is  a  very  good  size.  The  length  may  vary,  using  such  timber  as  can  be  most  conven- 
iently obtained  ;  still  it  is  better  to  have  them  from  16  ft.  to  20  ft.  long.  Of  course  greater 
length  is  in  no  wise  objectionable,  except  that  it  is  rather  more  difficult  to  obtain,  and  hence 


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FIG.  loi.—  N.  Y.,  W.  S.  &  B.  R.  R.  FIG.  102.— PENNSYLVANIA  R.  R.         FIG.  103.— TEXAS  &  PACIFIC  RY. 


V/rn — I    I  . 


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FIG.  104.— T.,  ST.  L.  &  K.  C.  R.  R.     FIG.  105.— K.  C.,  F.  S.  &  M.  R.  R.       FIG.  106.— ST.  P.,  M.  &  M.  RY. 


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FIG.  107.— C.,  C.  &  C.  R.  R.  FIG.  108.— M.,  K.  &  T.  RY.  FIG.  109.— L.  &  N.  R.  R. 

FIGS.  101  TO  109.— FLOOR    SYSTEMS. 


more  costly.  There  are  a  number  of  forms  of  joints  in  use  for  connecting  the  pieces  together. 
Many  of  these  are  shown  in  Figs,  no  to  115.  The  ordinary  halved  joint,  Fig.  114,  is  an 
excellent  one,  and  fully  answers  all  requirements.  The  joints  should  always  come  immediately 
over  a  tie  and  be  broken  ;  i.e.,  those  on  opposite  sides  should  be  over  different  ties,  no  two 
joints  coming  over  the  same  tie.  A  bolt  should  extend  through  the  joint  tie  and  outside 
stringer.  The  guard-rail  should  always  be  notched  down  at  least  I  in.  over  each  tie. 


r~r 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


37 


mm 


g  g 


FIG.  no.— N.  Y.,  W.  S.  &  B.  R.  R.  FIG.  111.— PENN.  R.  R.          FIG.  112.— T.,  ST.  L.  &  K.  C.  R.  R. 


2 


FIG.  113.— C.,  M.  &  ST.  P.  RY.  FIG.  114.— R.  &  D.  R.  R.  FIG.  115.— N.  Y.  ELEV.  ROADS. 

FIGS,  no  TO  115.— GUARD-RAIL  JOINTS. 

The  ends  of  the  guard-rails  at  either  end  of  the  bridge  ought  to  be  rounded  off  01 
cut  at  an  incline,  as  in  Figs.  116  and  117.  Every  tie  should  be  fastened  to  the  guard-rail 
in  some  way,  especially  when  they  are  not  fastened  to  the  stringers.  A 
bolt  should  be  put  through  the  guard-rail  at  every  fourth  or  fifth  tie,  and 
should  extend  through  the  outside  stringer.  The  balance  of  the  ties  may  FIG.  116.  FIG.  117. 
be  spiked  or  fastened  by  lag-screws.  Spiking  is  much  cheaper,  a  £-in.  X  GUARD-RAIL  ENDS. 
zo-in.  boat-spike  being  employed.  If  lag-screws  are  used,  a  f-in.  X  8-in.  screw  is  a  very  good 
size.  A  wrought  washer  is  to  be  placed  under  the  head  of  each  lag-screw,  and  a  3-in.  to  3^- 
in.  cast  washer  under  the  head  and  nut  of  each  bolt.  The  screw  or  nut  ends  of  the  bolts 
should  be  placed  up  so  that  they  may  be  more  easily  inspected  and  tightened.  It  is  not 
necessary  to  countersink  the  nuts  of  the  bolts  or  the  heads  of  the  lag-screws  ;  in  fact  it  should 
not  be  done  unless  absolutely  unavoidable,  as  the  holes  form  a  basis  for  the  lodgment  of 
water,  and  thus  are  apt  to  prove  very  harmful.  At  either  end  of  the  bridge  the  guard-rails 
should  extend  at  least  from  20  ft.  to  30  ft.  on  to  the  embankment,  and  be  flared  to  such  an 
extent  that  their  extreme  ends  will  be  the  gauge  of  the  track  from  the  rails.  They  should  be 
supplemented  by  bumping-posts  (Fig.  118).  These,  however,  will  be  spoken  of  later  on.  It 
is  better,  though  of  course  more  costly,  to  face  the  inside  upper  corner  of  the  guard-rails  with 
angle-iron.  This  overcomes  to  a  very  large  extent  the  tendency  of  the  wheels  to  override 
the  guards,  by  preventing  the  wheels  from  cutting  into  them.  Frequently  the  upper  edges 
of  the  guard-rails  are  bevelled.  This  is  bad  practice,  as  it  reduces  the  effective  height  of  the 
guard,  and  tends  to  assist  the  wheels  in  overriding  them. 

Inside  guard-rails,  either  of  wood  or  of  a  second  steel  rail,  placed  about  2\  in.  from  the 
rails,  are  claimed  by  many  to  be  much  more  efficient  than  outside  guards.  Outside  guards,  it 
is  said,  tend  to  turn  a  derailed  truck  at  right  angles  to  the  moving  train,  while  inside  guards 
turn  it  towards  the  track.  It  is  urged  against  inside  guards  that  articles  such  as  brake-shoes, 
etc.,  are  very  apt  to  fall  between  the  guard  and  the  rail,  and  thus  increase  the  number  of 
derailments.  However  this  may  be,  there  is  no  doubt  that  inside  guards  are  very  service- 
able, but  their  use  is  no  reason  for  omitting  the  use  of  outside  guards,  which  should  always  be 
employed.  In  regions  where  it  is  necessary  to  use  snow  ploughs  on  roads  where  the  pilot 
comes  very  close  to  the  rails,  inside  guards  should  never  rise  above  the  top  of  the  rails. 


38  A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 

Fastening  down  Floor  System. — There  are  a  number  of  different  methods  of  fastening 
the  floor  system  to  the  bents,  some  of  which  have  already  been  described.  Drift-bolting  the 
stringers  to  the  caps  is  the  one  most  generally  employed.  The  drift-bolts  should  extend  a 


FIG.  118. — EMBANKMENT  END  OF  TRESTLE,  SHOWING  FLARED  GUARD-RAILS  AND  BUMPING-POSTS. 

generous  distance  into  the  caps, — say  at  least  8  in.  One  drift-bolt  through  the  continuous 
piece  of  each  compound  stringer,  per  bent,  especially  if  the  ties  are  notched,  is  amply  suffi- 
cient (Fig.  1 19). 


u  u 


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1 


1 


FIG.  119. — DRIFT- BOLTING-DOWN  STRINGERS.  FIG.  120. — BOLTING-DOWN  STRINGERS. 

Among  the  other  ways  is  that  of  using  a  f-in.  bolt  with  nut  in  place  of  a  drift-bolt  (Fig. 
120).  This  bolt  is  sometimes  made  long  enough  to  extend  through  a  tie  placed  immediately 
above  the  cap,  in  which  case  it  usually  passes  through  the  space  between  the  stringer-pieces 

4  = 


FIG.  121.  FIG.  122. 

BOLTING-DOWN  STRINGERS. 

(Fig.  121).  Several  roads  employ  but  one  bolt,  placed  on  the  centre  line,  as  in  Fig.  121. 
Frequently  the  floor  system  is  not  fastened  to  the  bents  at  all,  its  weight  being  depended  on 
to  keep  it  down,  and  blocks  arranged  as  shown  in  Fig.  99,  and  Plates  n,  in,  XXIV,  XXVII,  etc.. 
Part  II,  to  keep  it  in  place  and  line.  In  this  case  girts,  securely  fastened  to  the  posts  at  their 
upper  ends,  should  always  form  a  part  of  the  structure,  no  matter  how  low  it  may  happen  to  be. 


CHAPTER   VI. 

BRACING,   COMPOUND-TIMBER   TRESTLES,   HIGH   TRESTLES,  TRESTLES  ON  CURVES, 

AND   MISCELLANEOUS  TRESTLES. 

Sway-bracing. — It  is  seldom  that  any  sway-bracing  will  be  needed  for  either  pile  or 
framed  bents  under  10  ft.  high.  For  those  from  10  ft.  to  20  ft.  in  height  a  single  X  of  3-in. 
X  iQ-in.  plank  is  all  that  is  necessary.  One  plank  should  be  placed  on  either  side  of  the  bent, 
and  extend  from  the  upper  corner  of  the  cap  across  to  the  lower  end  of  the  opposite  batter- 
pile,  terminating  just  above  the  ground,  or  to  the  opposite  lower  corner  of  the  sill  if  a  framed 
bent.  The  braces  should  be  bolted  to  the  cap,  to  each  pile  or  post,  and  to  the  sill  by  a  f-in. 
bolt,  with  a  cast  washer  under  both  head  and  nut.  Often  either  lag-screws  or  spikes  are  used 
for  attaching  the  braces,  but  bolts  are  to  be  preferred. 

For  bents  over  20  ft.  high  but  not  over  40  ft.  two  X's  of  sway-bracing  should  be  employed. 
It  is  both  more  convenient  and  more  economical  to  make  the  upper  X  of  a  constant  length, 
say  from  1 5  to  20  ft.,  and  put  the  odd  lengths  in  lower  one.  A  horizontal  stick  on  each  side 
of  the  bent  separates  the  X's.  These  sticks  are  also  made  of  3-in.  X  lO-in.  plank,  and  bolted 
to  each  post  or  pile. 

Whenever  a  pile  or  a  cap  extends  beyond  the  other  so  that  the  sway-braces  cannot  lie 
flat,  either  the  larger  of  the  two  should  be  sized  down  so  as  to  be  level  with  the  smaller,  or 
else  the  smaller  should  be  blocked  out  to  meet  the  brace.  In  general,  the  former  method  is 
the  better  one. 

Counter-posts. — When  framed  bents  approach  a  height  of  40  ft.,  they  are  frequently 
stiffened  by  the  use  of  counter-posts  rather  than  sway-bracing,  though  sometimes  by  the  use 
of  both.  The  employment  of  counter-posts  requires  the  dividing  of  the  bent  into  two  stories 
by  means  of  an  intermediate  sill.  Plates  XV,  XIX,  XXI,  XXIII,  XXIV,  Part  II,  show  several 
methods  of  using  counters.  They  are  more  generally  employed  in  very  high  work,  and  for 
further  particulars  in  regard  to  them  the  reader  is  referred  to  the  section  on  High  Trestles. 

Longitudinal  Bracing. — There  is  considerable  variation  in  the  methods  of  longitudinal 
bracing  employed,  some  bracing  every  bay,  others  only  every  third  or  fourth  ;  some  arranging 
the  braces  diagonally  or  latticed,  others  horizontally,  and  still  others  in  what  might  be  called 
a  laced  form.  Examples  of  all  of  these  forms  are  shown  in  Plates  XVI,  XXIX,  XI,  Part  II.  All 
possible  combinations  of  these,  especially  of  the  last  two,  are  employed,  as  well  as  many  modi- 
fications and  adaptations.  Plate  XI  illustrates  that  which  may  be  called  the  laced  form,  and 
is  the  standard  on  the  Pennsylvania  Railroad.  The  ends  of  the  braces  are  cut  in  the  form,  and 
the  edges  of  the  caps  and  sills  chamfered,  as  in  the  detail  drawing.  Each  piece  is  fastened  to 
both  cap  and  sill  by  a  heavy  cut  spike.  There  is  but  one  stick  of  8-in.  X  8-in.  material  to 
each  bay,  and  it  is  placed  in  the  centre  line  of  the  trestle.  When  horizontal  bracing,  such  as 
shown  in  the  side  elevation  in  Plate  XXIX,  Part  II,  is  used,  there  should  be  a  stick  placed 

39 


40  A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 

immediately  above  the  sill  on  the  outside  of    each    post,  and    one    immediately  above   the 
horizontal  piece  of  the  sway-bracing. 

Lateral  Bracing. — Lateral  bracing,  such  as  is  illustrated  in  Plate  ix,  Part  II,  adds  very 
greatly  to  the  stiffness  of  a  structure.*  It  is  made  of  two  6-in.  X  6-in.  timbers  placed  diag- 
onally across,  from  cap  to  cap,  immediately  beneath  the  stringers  and  bolted  together  at 
the  intersection  by  a  f-in.  or  |-in.  bolt.  The  timbers  are  usually  slightly  notched  into  the  caps, 
and  fastened  in  place  by  several  heavy  spikes.  This  kind  of  bracing  is  coming  into  quite 
general  use,  and  is  now  one  of  the  essentials  of  many  new  designs.  When  used,  the  longi- 
tudinal bracing  need  not  be  so  extensive.  It  is  said  that  where  lateral  bracing  is  employed 
the  trestle  keeps  in  line  much  better. 

Compound-timber  Trestles. — There  is  a  style  of  construction  very  largely  in  vogue 
which  may  be  denominated  as  above.  The  members,  such  as  caps,  sills,  posts,  etc.,  either 
wholly  or  partly,  are  each  composed  of  two  or  more  pieces  bolted  together  instead  of  being  a 
solid  stick.  The  parts  are  generally  separated  from  each  other  to  a  greater  or  lesser  degree. 
While  the  life  of  the  structure  may  be  somewhat  shortened  in  some  cases,  it  is  claimed  that 
this  disadvantage  is  more  than  offset  by  the  ease  of  repairs,  as  any  part  can  be  replaced  with  a 
minimum  amount  of  labor,  and  without  causing  the  least  disturbance  in  the  running  of  trains 
or  impairing  the  safety  in  anyway.  On  account  of  the  smaller  size  of  the  timber,  much  more 
thoroughly  seasoned  and  better  quality  material  can  be  obtained.  It  can  also  be  much  more 
easily  inspected.  The  sticks  are  generally  6  in.  X  12  in.  Several  plans  of  this  style  of  struc- 
ture are  given  in  Plates  XXVII,  XXVIII,  XXIX,  xxx,  and  XXXII,  Part  II. 

High  Trestles. — Trestles  above  40  ft.  in  height  may  be  classed  as  high  trestles.  Usually 
they  are  divided  into  two  or  more  decks  and  stories.  The  height  of  the  decks  depends  upon 
several  considerations,  but  is  regulated  to  a  certain  extent  by  the  length  of  timber  that  can 
be  most  economically  procured.  The  decks  and  stories  should  be  of  uniform  height  through- 
out any  one  trestle,  or  at  least  those  upon  the  same  level  should  be,  in  order  to  simplify  things 
as  much  as  possible,  and  the  odd  lengths  put  into  the  lowest  one.  It  is  in  the  designing  of 
these  rather  exceptional  structures,  especially  when  the  extraordinary  height  of  one  hundred 
or  more  feet  is  reached,  that  there  is  every  opportunity  for  the  full  employment  of  a  very 
high  grade  of  constructive  skill. 

There  may  be  said  to  be  four  classes  of  high  trestles : 

ist.  Those  in  which  the  posts  are  continuous,  being  made  up  to  the  required  length  by 
joining  single  sticks  together,  end  to  end,  with  a  butted  joint,  using  splice-blocks  or  other 
means. 

2d.  Those  in  which  the  decks,  though  separate  and  distinct,  are  still  intimately  joined 
together  by  means  of  framing ;  the  sill  of  one  deck  acting  as  the  cap  of  the  one  beneath. 

3d.  Those  in  which  the  decks  are  separated  entirely  by  purlins  or  other  means. 

4th.  Those  in  which  the  posts,  and  frequently  other  members,  are  each  made  up  of  two 
or  more  pieces  placed  together  side  by  side.  In  this  latter  group  are  included  cluster-bent 
trestles. 


*  Adopted   as   standard   on  the  Boston   &   Albany    Railroad;    the  Toledo  &  Ohio  Central   Railroad, 
C.  Buxton,  Chief  Engineer. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  41 

Those  of  the  first  class  are  generally  erected  where  good  quality  long  timber  of  large 
size  may  be  easily  and  economically  procured.  In  this  group  stories  are  formed  by  bolting 
horizontal  pieces  of  timber  to  the  posts,  one  on  either  side,  at  the  proper  heights.  Counter- 
posts,  or  what  may  be  called  inside  batter-posts,  are  often  introduced,  a  new  set  being  put  in 
at  every  other  story,  and  continued  down  to  the  main  sill.  This  class  of  trestle  is  shown  very 
clearly  in  Part  II,  Plates  XV,  XVI,  and  xvill.  In  Plates  XV  and  xvm  the  employment  of 
counters  is  depicted. 

Classes  2  and  3  are  resorted  to  when  but  comparatively  short  timber  can  be  procured, 
and  for  several  reasons  are,  in  the  writer's  judgment,  rather  to  be  preferred,  especially  the 
third  class,  to  the  continuous-post  group.  The  second  class  hardly  needs  any  enlargement,  as 
the  mere  defining  of  it  at  once  describes  its  peculiarity.  The  posts  are  generally  connected 
with  sills  and  caps  in  this  type  by  mortise  and  tenon  joints.  All  posts  should  of  course  come 
immediately  beneath  those  in  the  deck  above,  and  be  in  the  same  line  with  them,  forming  to 
all  intents  and  purposes  a  continuation  of  them.  Illustrations  of  this  type  are  given  in  Part 
II,  Plates  xix  to  xxii. 

In  the  third  class  the  bents  of  each  deck  are  distinctly  separate^eing  framed  entirely  by 
themselves.  The  lower-deck  bents  are  erected,  and  then  purlins  laid  along  on  the  caps  in 
such  a  way  as  to  come  directly  under  the  posts  of  the  deck  above,  the  bents  of  which  are  of 
course  placed  directly  over  those  of  the  one  below.  Purlins  are  laid  on  the  caps  of  these,  and 
the  next  deck  erected  on  top  of  them.  This  is  continued  until  the  necessary  height  has  been 
attained.  The  purlins  should  be  firmly  fastened  to  the  caps  on  which  they  rest  either  by 
ordinary  bolts  or  by  drift-bolts.  The  sills  should  also  be  secured  to  the  purlins  underneath 
them  in  the  same  manner.  For  illustrations  of  this  construction  see  Plates  XXIII  to  XXVI. 
This  style  offers  many  advantages  for  ease  of  erection,  which  will  be  more  readily  appreciated 
when  that  subject  is  treated  of. 

The  fourth  class  may  be  subdivided  into  two  groups,  namely,  those  in  which  the  posts, 
and  sometimes  other  members,  are  built  up  by  bolting  two  or  more  pieces  together,  keeping 
them  separated  a  little  from  each  other  (see  Part  II,  Plates  xxvil,  XXX,  XXXI,  etc.), — the 
majority  of  them  might  almost  be  called  plank  trestles, — and  those  in  which  each  post  is 
made  up  of  four  smaller  posts,  two  of  the  smaller  posts  always  being  continuous  over 
any  one  story :  these  are  known  as  cluster-bent  trestles.  Both  of  these  styles  are  claimed 
to  have  a  number  of  advantages  over  those  built  with  single  sticks  of  large  dimensions. 
Among  them  may  be  mentioned  the  ability  to  secure  better  material,  both  as  respects 
quality  and  seasoning,  on  account  of  the  pieces  being  smaller ;  greater  economy  and  ease  in 
the  cost  of  erection  ;  and  especially  greater  facility  for  making  repairs.  It  is  also  claimed  that 
they  can  be  much  more  thoroughly,  easily,  and  certainly  inspected.  While  it  is  said  that  their 
life  is  hardly  as  long  as  that  of  the  others,  still  the  advantages  enumerated,  it  has  been  stated, 
greatly  offset  this  disadvantage.  Besides*  they  may  be  kept  in  a  much  safer  condition. 

In  all  of  the  different  styles  the  bents  should  always  be  thoroughly  sway-braced,  each  story 
and  deck  having  its  own  set  of  braces.  There  should  always  be,  also,  a  set  of  longitudinal 
braces  to  each  deck.  As  a  rule  these  are  of  the  horizontal  type.  It  should  not  be  attempted 
to  economize  in  the  amount  of  timber  by  reducing  either  the  number  or  the  size  of  the  girts. 


42  A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 

Scanting  the  amount  of  longitudinal  bracing  is  in  no  case  real  economy :  it  is  in  fact  outrageous, 
tending  to  great  danger  to  human  life.  Frequently  two  adjacent  bents  every  three  or  four 
bents  apart  are  connected  by  diagonal  longitudinal  braces  so  as  to  form,  in  effect,  towers 
similar  to  those  of  iron  trestles.  While  this  is  an  excellent  plan,  the  longitudinal  bracing  of 
the  intermediate  spans  should  not  be  left  out,  as  is  generally  the  case;  for  while  the  tower 
construction  adds  considerably  to  the  stiffness  of  the  structure  as  a  whole,  it  is  no  excuse 
whatever  for  weakening  the  remaining  parts.  To  the  writer  it  seems  that  the  best  form  of 
high  trestle  is  the  cluster-bent  type,  with  every  third  bay  braced  diagonally  so  as  to  form  a 
tower,  and  with  the  intermediate  bays  braced  with  horizontal  sticks  at  every  deck,  a  3  X  10  in. 
plank  being  placed  on  each  side  of  every  post. 

The  plentiful  use  of  counter-posts  is  also  to  be  recommended.  For  giving  lateral  stiffness 
to  the  structure,  the  lateral  bracing  described  on  page  40,  and  illustrated  in  Part  II,  Plate  IX, 
is  very  effective,  and  should  be  used  whenever  possible. 

Considerable  economy  may  be  effected  in  trestles  of  great  height  by  spacing  the  bents 
farther  apart,  say  thirty  feet,  and  supporting  the  floor  on  a  deck  truss.  Such  a  construction 
is  shown  in  Part  II,  Plates  XXXIII  and  XXXIV. 

The  floor  system  for  high  trestles  is  of  course  the  same  as  that  for  the  lower  structures, 
and  which  was  discussed  fully  in  Chapter  V. 

A  far  more  thorough  knowledge  of  the  various  practice  in  the  treatment  of  these  struc- 
tures may  be  obtained  by  the  careful  study  of  the  plates  in  Part  II,  than  could  be  im- 
parted by  mere  descriptive  matter,  and  so  the  reader  is  referred  to  them. 

Trestles  on  Curves. — Of  course,  whenever  it  is  possible,  building  a  trestle  on  a  curve 
should  be  avoided.  Sometimes,  however,  this  cannot  be  helped,  and  then  we  have  to  resort 
to  the  best  means  at  our  command  to  increase  their  strength  and  safety.  It  is  preferable  to 
place  the  bents  on  radial  lines,  especially  where  the  curve  is  a  sharp  one.  The  bracing  of  all 
kinds  should  be  heavier  and  more  abundant  than  where  the  structure  is  on  a  tangent.  It  is 
also  well  to  give  the  batter-posts,  especially  those  on  the  outside  of  the  curve,  as  much  incli- 
nation as  possible,  a  batter  of  3^  in.  to  4  in.  per  foot  not  being  out  of  the  way,  so  as  to 
increase  the  breadth  of  the  base,  and  enable  the  trestle  to  better  resist  the  centrifugal  force 
of  the  train. 

Lateral  bracing  should  always  be  employed  on  curved  trestles,  as  it  tends  to -save  the 
structure  considerably  from  the  racking  it  otherwise  receives  from  the  train. 

There  are  six  different  ways  of  elevating  the  outer  rail  in  common  use.  The  first 
is  by  cutting  the  piles  or  posts  so  as  to  give  the  cap  the  proper  inclination;  the  second, 
by  tapering  the  tie,  as  in  Plate  xxxvi,  Part  II  ;  the  third,  by  placing  wedge-shaped 
blocks  between  the  tie  and  the  stringer,  and  bolting  them  to  the  former,  as  in  Fig.  123  ; 
the  fourth,  by  shiming  up  the  track  by  wedge-shaped  blocks  placed  on  top  of  the  ties, 
and  securely  spiked  to  them,  as  in  Fig.  124;  the  fifth,  by  placing  a  bolster  or  corbel 
under  the  stringers  on  one  side  and  not  on  the  other;  and  the  sixth,  by  notching  or  sizing 
down  one  end  of  the  cap,  as  in  Fig.  125.  This  latter  method  is  in  use  on  the  Clinch  Valley 
Division  of  the  Norfolk  &  Western  Railroad,  and  the  dimensions  given  in  the  figure  are  for  a 
6°  curve.  The  other  methods  arc  in  use  on  numerous  roads  throughout  the  country. 

One  very  serious  objection  urged  against  the  second  method  is  the  splitting  of  the  tie  by 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


43 


the  jarring  of  the  trains;  another,  the  increased  cost  of  the  tie,  because  a  tie  having  the  cross- 
section  of  the  largest  end  has  to  be  paid  for.  When  this  method  is  used,  the  face  on  which 
the  fibres  are  cut  across  diagonally  should  always  be  placed  down. 


n~TY 

Wv«* 


FIG.  123. 


FIG.  124. 


H* a/g'— +7T3/' 


i^ 

FIG.  125. 
FIGS.   123  TO  125.— METHODS   OF   ELEVATING   TRACK    ON   CURVED   TRESTLES. 

Examples  of  trestles  built  on  curves  are  given  in  Part  II,  Plates  IX  and  XXXVI. 

Double-track  Trestles. — Double-track  trestles,  as  a  rule,  are  little  else  than  two  single 
track  trestles  placed  side  by  side  and  intimately  joined  together.  The  caps  and  sills  should 
always  be  continuous.  The  two  batter-posts  or  piles  which  would  come  in  the  centre  are 
replaced  by  a  single  vertical  post  or  pile,  or  else  entirely  omitted,  and  a  heavy  guard-rail  is 
bolted  to  the  ties  about  half-way  between  the  inside  rails.  An  outside  or  "jack"  stringer 
should  always  be  placed  beneath  this  guard-rail,  and  secured  firmly  in  place.  No  scanting  of 
the  fastening  on  account  of  its  interior  position  should  be  allowed.  Plates  IX  and  XXXV  to 
XXXVH,  Part  II,  show  several  double  track  trestles. 

Knee-braced  Trestles. — On  unimportant  branch  lines,  where  the  traffic  is  light  and  the 
trestles  high,  considerable  economy  in  timber  is  attained  by  using  the  knee-braced  type  of 
trestle.  In  this  form  every  other  bent  is  omitted,  making  the  spans  just  twice  the  ordinary 
length.  The  stringers  are  strengthened  by  placing  a  short  straining-beam  beneath  them,  and 
running  knee-braces  from  either  end  of  it  down  against  the  posts.  Many  engineers  object 
very  strongly  indeed  to  using  this  form  of  construction  at  all.  Plate  XVI,  Part  II,  shows  a 
form  of  this  type  of  trestle,  which  is  the  standard  on  the  Norfolk  &  Western  Railroad. 

Round-timber  Trestles. — It  frequently  happens  that  it  is  rather  difficult  to  obtain 
sawed  timber,  and  extensive  hewing  is  both  expensive  and  unnecessary.  In  this  case  the 
trestle  is  built  of  round  timber.  This  form  of  structure  is  exceedingly  cheap,  and  if  well  built 
is  very  serviceable,  though  rather  rough  and  unfinished  in  appearance. 

Trestles  with  Solid  Floors. — On  the  line  of  the  Louisville  &  Nashville  Railroad, 
between  Mobile  and  New  Orleans,  there  are  some  trestles  of  very  peculiar  construction.  The 


44  A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 

floor  is  made  in  the  form  of  a  trough  and  filled  in  with  earth.  The  ties  and  rails  are  then  laid 
on  top  of  this  filling,  the  same  as  on  an  ordinary  embankment.  For  certain  climates  and 
regions  this  construction  has  much  to  recommend  it.  It  is  especially  adapted  to  mild  south- 

o 

ern  climates,  and  is  almost  absolutely  protected  against  destruction  by  fire  from  cinders 
dropped  by  a  locomotive.  All  of  the  timber  should  be  thoroughly  creosoted  Plate  VIII, 
Part  II,  shows,  very  clearly,  one  of  these  trestles. 


CHAPTER    VII. 


IRON   DETAILS. 

Spikes. — There  are  two  varieties  of  spikes  used  in  trestle-building, — cut  spikes  and  boat: 
or  ship  spikes.  Cut  spikes  (Fig.  126)  are  fashioned  after  the  same  pattern 
as  common  nails,  and  are  essentially  stamped  out  of  sheet-metal.  They 
should  be  of  good  quality  and  have  generous-sized  heads.  Table  X  gives 
the  number  of  cut  spikes  in  a  keg  of  100  Ibs.,  and  also  the  weight  in  pounds 
of  a  single  spike. 

TABLE  X. 

Cut  Spikes. 


FIG.  126.    FIG.  127. 
CUT  BOAT- 

SPIKE.          SPIKE. 


Length  in 
inches. 

No.  in  Keg, 
100  Ibs. 

Weight  of  one 
Spike,  Ibs. 

Length  in 
inches. 

No.  in  Keg, 
loo  Ibs. 

Weight  of  one 
Spike,  Ibs. 

* 

2900 
2IOO 

•0344 
.0476 

Si 

6 

850 

775 

.1176 
.1293 

4 

1500 

.0667 

63 

575 

•1739 

5" 

II5O 
950 

.0869 
.1052 

7 
8 

450 

375 

.  2222 
'.2666 

Occasionally  common  nails  of  the  larger  sizes  have  a  limited  use,  and 


as  an  aid  in  estimating,.  Table  XI,  giving  their  size  and  weight,  is  appended. 

TABLE  XL 

Size  and  Weight  of  Nails. 


Name. 

Length. 

No.  in  a  Ib. 

io-penny  common. 

3  inches 

60 

12 

3i 

44 

16 

3i 

32 

20 

4 

24 

3° 

4i 

18 

40 

5 

H 

50 

Si 

12 

60 

6 

IO 

8 

fence. 

2i 

5° 

10 

tt 

3 

34 

12 

« 

3i 

29 

These  nails  are  of  the  same  pattern  as  the  spike  shown  in  Fig.  126,  but  smaller.  Boat- 
spikes  are  forged  from  bars  of  wrought-iron,  and  are  of  the  general  shape  shown  in  Fig.  127. 
They  have  a  square  section,  and  are  sharpened  at  the  end  to  a  kind  of  blunt  chisel-point. 
This  kind  of  spike  is  the  one  most  commonly  used  in  building  trestles,  and  is  always  the  kind 

to  be  employed  in  fastening  guard-rails  to  ties  and  ties  to  stringers.     Table  XII  gives  the 

45 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


approximate  number  of  boat-spikes  in  a  keg  of  150  Ibs.  in  heavy-faced  type,  and  the  weight 
of  a  single  spike  in  light-faced  type. 

TABLE  XII. 

Number  of  Boat-spikes  in  a  Keg  of  150  Ibs.  and  Weight  of  a  Single  Spike. 


1/1 

-*« 

u 
1H  "i 

H  | 

Length  in  Inches. 

3 

3* 

4 

4i 

5 

5i 

6 

6J 

7 

71 

8 

8* 

9 

9* 

IO 

i 

1910 

.0785 

1585 
.0946 

1326 

.1093 

1223 

.1226 

1025 

.1463 

A 

1010 

.1485 

963 

•1557 

810 

.1851 

605 

.2479 

583 

.2572 

52i 

.2879 

TV 

542 

.2767 

503 

.2982 

461 

•3253 

423 

•3546 

402 

•3731 

321 

•4673 

I 

340 

.4117 

312 

4839 

298 

•5°33 

280 

•5357 

261 

•5747 

240 

.625 

223 

.6726 

A 

221 

.6787 

200 

•75 

190 

.7881 

180 

.2333 

170 

.8823 

1  60 

•9375 

ISO 

I.OOOO 

140 

1.0714 

130 

1.1538 

1 

140 

1.0714 

130 

1.1538 

120 

1.25 

no 

1.3636 

IOO 

1.5000 

Drift-bolts. — The  common  form  of  drift-bolt  is  but  little  else  than  a  very  long  boat- 
spike,  though  other  shapes  are  used  quite  extensively.  They  should  always  be  long  enough 
to  penetrate  the  last  timber  desired  to  be  held  to  a  depth  sufficient  to  give  a  good  firm  hold. 
Fig.  128  gives  the  forms  of  bolts  in  general  use,  the  first  one  being 
that  most  commonly  employed.  They  are  usually  made  of  iron  hav- 
ing a  section  f  in.  square  or  a  diameter  of  f  in.,  and  for  fastening 
12-in.  caps  to  posts  or  piles  are  generally  20  in.  long.  Their  weight  is 
about  as  given  in  Table  XIII. 

TABLE  XIII. 

Weight  of  Drift-bolts. 


-f     \ 
V 

\ 

L_ 

J 

\ 
J           M 

FK;.  128.— DRIFT-BOLTS. 


Square  Section. 

Round  Section. 

Length 

in  Inches. 

i"  Sq. 

i"  Sq. 

J"  Diam. 

i"  Diam. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

18 

2.9 

5-i 

2-3 

4.0 

20 

3-2 

5-7 

2-5 

4-4 

22 

3-5 

6.2 

2.8 

4.9 

24 

3-8 

6.8 

3-o 

5-3 

26 

4.1 

7-3 

3-3 

5.8 

The  main  value  of  drift-bolts  lies  in  their  holding  power.     Following  is  a  summary  of 
three  series  of  experiments  upon  this  subject:* 


Ncivs,  Feb.  28,  1891. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  47 

U.  S.  Government  Experiments. — These  experiments  were  made  under  the  direction  of 
General  Weitzal  by  Assistant  U.  S.  Engineers  A.  Noble  and  C.  P.  Gilbert,  in  1874-77,  and 
were  published  by  Colonel  O.  M.  Poe  in  his  report  to  the  Chief  of  Engineers  for  1884.  This 
series  was  very  extensive,  but  the  valuable  results  obtained  are  robbed  of  much  of  their  value 
by  the  lack  (in  the  original  publication)  of  suitable  comparisons  and  conclusions. 

The  mean  of  from  150  to  200  experiments  with  round  and  square  bolts,  both  ragged  and 
smooth,  in  different-sized  holes,  shows  that  the  resistance  after  having  been  driven  seven 
months  is  10  per  cent  greater  than  the  resistance  immediately  after  driving,  the  different  sizes 
and  forms  being  strikingly  uniform.  The  mean  of  150  experiments  under  various  conditions 
shows  that  the  resistance  to  being  drawn  in  the  direction  which  it  was  driven  is  only  60  per 
cent  of  its  resistance  to  being  drawn  in  the  opposite  direction  ;  that  is  to  say,  the  resist- 
ance to  being  drawn  through  is  only  60  per  cent  of  that  to  being  drawn  back.  The  mean  of 
50  experiments  shows  that  smooth  rods  have  a  greater  holding  power,  both  to  being  drawn 
through,  and  also  to  being  drawn  back,  than  ragged  ones,  a  "  moderate  ragging"  reducing 
the  resistance  a  little  more  than  25  per  cent,  and  an  "  excessive  ragging"  reducing  the  holding 
power  more  than  50  per  cent. 

Concerning  the  best  relation  between  the  diameter  of  the  bolt  and  that  of  the  hole,  one 
series  of  60  experiments,  shows  that  the  holding  power  of  a  i-in  round  rod  in  a -j-^  hole  is 
greater  than  in  either  a  i|-  or  in  a  |-|  hole,  the  resistance  in  the  i|-  hole  being  98  per  cent,  in 
the  -[f  90  per  cent,  of  that  in  the  {-^-  hole.  On  the  other  hand,  another  series  of  35  experi- 
ments makes  the  resistance  in  a  |f  hole  greater  than  in  a  |f  or  a  •ff,  the  first  two  being  prac- 
tically the  same,  and  the  last  being  only  85  per  cent  of  the  first.  However,  the  difference 
between  the  two  series  is  not  material,  considering  the  nature  of  the  experiments.  For  a  f-in. 
round  bolt,  four  experiments  on  each  size  seem  to  prove  that  the  holding  power  in  a  ^-|  hole 
is  about  one  quarter  greater  than  in  a  T9^  or  an  -j--^  hole.  For  a  I-in.  square  bolt,  the  holding 
power  in  a  ||-  hole  is  only  a  trifle  greater  than  in  a  |f ,  and  about  20  per  cent  greater  than  in 
a  ^f-  hole,  as  deduced  from  20  to  40  experiments  for  each  size  of  hole. 

The  holding  power  of  a  i-in.  square  bolt  in  a  ||-  hole  was  practically  the  same  as  for  a 
i-in.  round  rod  in  an  -j-g-in.  hole.  There  is  25  per.  cent  more  metal  in  the  square  drift-bolt, 
while  more  labor  is  required  to  bore  a  -ff -in.  hole  than  an  j^-in.  one ;  therefore  the  round 
drift-bolt  is  at  least  25  per  cent  more  efficient  per  pound  of  metal  than  the  square  one. 

The  holding  power  of  a  i-in.  round  bolt  in  a  -ff-in.  hole  in  white  pine,  when  drawn  back 
immediately  after  driving,  is  a  trifle  over  10,000  Ibs.  per  linear  foot  of  bolt,  a  mean  of  42 
experiments  on  7  pieces  of  timber.  Twelve  experiments  on  3  sticks  of  Norway  pine,  under 
conditions  similar  to  the  preceding,  gave  9000  Ibs.  per  linear  foot  of  bolt.  Experiments  upon 
4  sticks  of  hemlock  seem  to  show  that  the  resistance  is  practically  the  same  as  white  pine. 

One-inch  round  screw-bolts  were  screwed  into  ^-|,  ||,  and  Tf-in.  holes  and  immediately 
drawn  back,  the  result  being  that  there  was  but  little  difference  for  the  different-sized  holes. 
Half  of  the  bolts  had  8  threads  to  the  inch  and  half  had  12,  the  latter  giving  a  very  little  the 
greater  resistance.  The  resistance  for  the  screw-bolts  was  about  50  per  cent  more  than  the 
maximum  resistance  of  the  plain  round  rods. 

The  report  says :  "  Two  classes  of  blunt  points  were  used  :  Long,  blunt  points,  tapered 
back  for  a  distance  of  i£  to  2  in.  and  reduced  to  a  round  section,  on  square  as  well  as  round 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


bolts,  with  a  diameter  less  than  that  of  the  hole  into  which  it  was  driven.  They  were  pointed 
hot.  Short,  blunt  points  were  reduced  in  size  at  an  angle  of  about  45°  by  cold  hammering, 
the  point  of  the  square  bolt  remaining  square,  with  rounded  corners,  the  intention  being  more 
to  remove  all  cutting  edges  from  the  point  than  to  reduce  it  much  in  size  or  change  the 
square  sections  to  round."  The  experiments  were  not  so  arranged  as  to  make  it  possible  to 
draw  any  reliable  conclusion  as  to  the  relative  merits  of  the  two  forms  of  points ;  but  if  the 
experiments  show  anything  in  this  respect,  it  is  that  the  resistance  of  bolts  having  "long, 
blunt  points"  is  about  ten  per  cent  more  than  those  having  "  short,  blunt  points." 

Brooklyn  Bridge  Experiments. — Experiments  made  in  connection  with  the  construction 
of  the  East  River  Bridge  by  Mr.  F.  Collingwood  and  Colonel  Paine,  and  communicated  by  the 
former,  gave  a  holding  power  of  12,000  Ibs.  per  linear  foot  of  bolt  for  a  i-in.  round  rod  driven 
into  a  |f -in.  h°le  m  first  quality  Georgia  pine,  and  a  resistance  of  15,000  Ibs.  in  a  T|-in.  hole. 
It  was  found  that  in  lighter  timber  containing  less  pitch  the  holding  power  was  about  20  per 
cent  less ;  and  in  very  dense  wood,  containing  more  pitch,  about  10  per  cent  more. 

University  of  Illinois  Experiments: — A  third  series  of  experiments  was  made  by  Mr.  J.  B. 
Tscharner  in  the  testing  laboratory  of  the  University  of  Illinois,  and  published  in  full  in  "  No. 
4,  Selected  Papers  of  the  Civil  Engineers'  Club  of  the  University  of  Illinois."  According  to 
these  experiments,  the  average  holding  power  of  a  i-in.  round  rod  driven  into  a  Tf-in,  hole  in 
pine,  perpendicular  to  the  grain,  is  6000  Ibs.  per  linear  foot ;  and  under  the  same  conditions 
the  holding  power  in  oak  is  15,600  Ibs.  per  linear  foot.  The  holding  power  of  the  bolt  driven 
parallel  to  the  grain  is  almost  exactly  half  as  much  as  when  driven  perpendicular  to  the  grain. 
If  the  holding  power  of  a  i-in.  rod  in  a  Tf-in.  hole  be  designated  as  I,  the  holding  power  in  a 
|f-in.  hole  is  1.69;  in  a  Tf-in.  hole,  2.13;  and  in  a  T-|-in.  hole,  1.09.  The  holding  power 
decreases  very  rapidly  as  the  bolt  is  withdrawn. 

Dowels. — In  place  of  drift-bolts  with  point  and  head,  plain  iron  bars,  either  square  or 
round,  are  frequently  resorted  to.  These  are  not  forged  or  altered  in  any  way,  but  are  placed 
in  the  structure  in  just  the  condition  that  they  are  sheared  from  the  rods,  the  only  precaution 
taken  being  to  see  that  they  are  straight. 

The  ties  are  frequently  dowelled  to  the  stringers.  Pins  made  of  f-in.  round  iron  cut  into 
pieces  5  in.  long,  are  of  a  very  good  size.  They  weigh  0.4304  Ib.  each. 

One  method  of  fastening  the  posts,  caps,  and  sills  together  is  by  means  of  dowels,  f  in. 
by  8  in.,  which  weigh  about  one  pound  each. 

The  following  list  gives  the  weight  of  one  inch  of  a  bar  of  iron  of  the  various  diameters 
most  frequently  employed  in  this  kind  of  work : 


I  inch  square, 0.2806  Ib. 

i     "     diam.  round,     .     .     .  0.2204  " 

£     "     square, 0.2149  " 

|     "     diam.  round,      .     .     .  0.1687" 

£     "     square, 0.1579" 


|  inch  diam.  round,      .     .     .  0.1240  Ib. 

|     "     square 0.1096" 

f     "     diam.  round,      .     .     .  0.0860  " 

\    "    square 0.0701  " 

\     "     diam.  round,          .     .  0.0551  " 


Bolts. — Bolts  for  holding  the  stringer-pieces  together,  fastening  on  the  braces,  guard- 
rails, etc.,  are  made  of  f-in.  round  iron.     They  vary  in  length  of  course,  according  to  the  use 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


49 


they  are  intended  for.     A  head  should  be  forged  on  one  end,  and  a  good,  deep,  well-formed 

right-hand  thread  cut  upon  the  other  for  an  appropriate  distance.     There  are  three 

• 

kinds  of  heads  in  use  in  trestle-building:  the  round  or  button  head,  the  flat  coun- 
tersunk head,  and  the  ordinary  square  head  (Fig.  129). 

Square  nuts  with  a  thickness  equal  to  the  diameter  of  the  bolt,  and  each  side  to 
twice  the  diameter,  are  the  best.     The   outer  top  corners  of  the  nuts  and  square 
heads  should  be  chamfered.     A  cast-iron  washer,  from  3  in.  to  3^  in.  in  diameter,  is 
to  be  placed  beneath  both  head  and  nut  of  all  bolts.     The  bolts  are  driven  through  *^ 
holes  bored  in  the  timber,  and  which  should  be  -fa  in.  less  in  diameter  than  the  bolts,   FIG.  129. 
so  as  to  insure  a  snug  fit.  BOLTS. 

While  the  weight  of  the  bolt  will  be  somewhat  affected  by  the  shape  of  the  head,  still 
the  weight  given  in  Table  XIV  may  be  used  in  making  up  preliminary  estimates,  as  the  error 
will  be  on  the  safe  side ;  i.e.,  too  heavy. 

TABLE  XIV. 

Approximate  Weight  of  Bolts  in  Lbs.,  with  Square  Heads  and  Nuts,  including  both. 


Length 
under 
Head  in 
Inches. 

Diameter  in  Inches. 

•2' 

f 

t 

I 

i 

6 

0.59 

1.  01 

7 

O.64 

I.  10 

8 

O.70 

1.19 

9 

0.75 

.27 

10 

0.81 

-36 

2.IO 

3-°5 

4-23 

ii 

0.86 

•44 

2.22 

3.22 

4-45 

12 

0.92 

•53 

2-35 

3-39 

4.67 

13 

0.97- 

.62 

2.47 

3-55 

4.89 

H 

1.03 

.70 

2.59 

3-72 

5.11 

IS 

1.08 

•79 

2.72 

3-89 

5-34 

16 

.87 

2.84 

4.06 

5.56 

17 

.96 

2.97 

4.23 

5-78 

18 

2.05 

3-°9 

4.40 

6.00 

19 

3-21 

4-57 

6.22 

20 

3-34 

4-74 

6.44 

21 

3-46 

4.90 

6.66 

22 

3-59 

5.07 

6.88 

23 

3-7i 

5.24 

7.10 

24 

3.83 

5.41 

7-32 

In  ordering  bolts  the  term  "grip"  is  sometimes  employed,  meaning  the  total  thickness  of 
the  material  to  be  held  together,  or,  in  other  words,  the  distance  between  the  inside  faces  of 
the  washers. 

Lag-screws. — A  lag-screw  (Fig.  1 30)  is  little  more  than  a  very  large  wood-screw,  with 

a  square  head  similar  to  a  bolt-head.     A  hole  the  full  size  of 
the  shank  should  be  bored  through  the  first  timber,  otherwise 

the  screw  will  not  draw  the  timbers  together.     For  the  balance 
FIG.  130.— LAG-SCREW. 

of  the  distance  the  hole  should  be  bored  much  smaller.     Under 

the  head  of  each  screw  a  wrought  washer  should  be  placed.     The  following  table  gives  the 
details  of  the  proper  size  of  washer  to  use  for  different-sized  lag-screws : 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


TABLE  XV. 

Proper  Size  of  Wrought  Washers. 


Diam.  Lag-screw. 

Diam.  of  Washer. 

Diam.  of  Hole. 

Thickness 
Wire-gauge. 

No.  In  150  Ibs. 

Weight  of  one 
in  Ibs. 

^  inch 

if  inches 

-&  inch 

No.  12 

4500 

•0333 

*    " 

if      " 

•H    " 

"      10 

2500 

.06 

f     " 

2 

\l    " 

"      IO 

t6oo 

.0938 

Separators,  Thimbles,  Packing  Washers. — These  were  described  when  treating  of 
stringers.  They  are  made  of  cast-iron,  which  should  be  of  good  quality  and  free  from  blow- 
holes. Table  XVI  gives  their  dimensions  and  approximate  weight. 

TABLE  XVI. 

Details  of  Cast-iron  Separators  (see  Figs.  62  to  72). 


Dimensions  in  Inches. 

Kind. 

Diam.  of  Rims 
or  Ends. 

Thickness  of 
Rim. 

Breadth  of  Rim 
or  Ends. 

Thickness     of 
Disk  or  Length 
of  Spool  from 
Outside    Face 
to    Outside 

Diam.  of  Hole. 

Diam.  of  Spool 
or      Smallest 
Diameter. 

Weight 
in  Ibs. 

Face  of  Ends. 

Fig.  62 

3 

I 

1 

i-7 

63 

3 

1 

I 

i 

1 

1.03 

64 

3 

3 

~g 

IJ 

£ 

1 

1-5 

65 

3T3ir 

\ 

Ii 

i 

Ii 

2tV 

66 

2i 

i 

I 

A 

f 

0.6 

67 

4 

I 

4i 

1 

2 

5-5 

68 

4 

i 

3 

i 

a 

3-25 

69* 

4 

1 

I 

i-7 

70 

4 

t 

6 

1 

i* 

3-75 

7i 

3 

2 

2 

i 

2 

2.5 

72 

3 

i 

4 

i 

It 

i-75 

*  The  six  smaller  holes  are  £"  in  diameter. 


Washers.  —  Cast-iron  washers  are  used  very  extensively.     They  are  always  placed  under 
the  heads  and  nuts  of  all  bolts  in  the  structure.     Fig.    131    gives  a  few  of  the  designs  in 


8CAtew 

,9   iv  2"  a*  ^   B'.  e' 


FIG.  131. — CAST-IRON  WASHERS. 


use,  and  Table  XVII  their  weight  and  dimensions.  The  solid  washers  are  placed  under 
the  heads  of  the  bolts,  and  those  having  either  a  slot  or  second  hole  in  them  under  the 
nuts.  The  purpose  of  these  slots  or  holes  is  to  enable  a  nail  to  be  driven  in  close  to  the  nut 
after  it  has  been  screwed  down  tight,  to  serve  as  a  nut-lock. 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 
TABLE  XVII. 

Details  of  Cast-iron  Washers. 


Dimensions  in  Inches. 

Kind. 

Weight 

Fig.  131- 

Diam.  of 
Back. 

Diam.  of 
Face. 

Diam.  of 
Hole. 

Thickness. 

in  Ibs. 

A 

3 

2i 

I 

i 

B 

3 

If 

1 

f 

C 

3i 

2i 

I 

f 

D 

3 

2 

I 

I 

E 

2| 

If 

1 

i 

F 

3 

Ii 

i 

f 

G 

4t 

2f 

1 

i 

H 

3 

2 

f 

f 

I 

4 

2 

I 

f 

J 

si 

2* 

T    3 

••ft 

f 

Sim  lar  to  B 

3i 

2 

I 

f 

1.25 

"  G 

4i 

2 

I 

f 

1-375 

As  wrought-iron  washers  are  used  to  a  greater  or  lesser  extent  in  this  class  of  work,  a 
table  giving  the  details  of  the  standard  washers  as  now  manufactured,  is  appended. 

TABLE  XVIII. 

Showing  the  Average  Number  of  Wrought-iron  Washers  in  a  Keg  of  150  Ibs.,  of  each  Standard  Size, 

As  adopted  by  "The  Association  of  Bolt  and  Nut  Manufacturers  of  the  U.  S." 


Diameter. 

Size  of  Hole. 

Thickness  Wire-gauge. 

Size  of  Bolt. 

No.  in  150  Ibs. 

i 

i 

No.  18 

A 

80.000 

f 

A 

"   16 

i 

34.285 

f 

A 

"  16 

i 

22.OOO 

1 

1 

"   16 

T5* 

18.500 

I 

A 

"  H 

f 

10.550 

Ii 

i 

"   H 

A 

7.500 

If 

T9* 

"    12 

i 

4.500 

Ii 

i 

"    12 

A 

3.850 

If 

H 

"    10 

i 

2.500 

2 

H 

"    IO 

f 

1.  600 

2i 

H 

"     9 

1 

1.300 

2i 

IA 

9 

i 

950 

2f 

it 

"     9 

i* 

700 

3 

it 

"     9 

ii 

550 

3i 

H 

9 

if 

450 

These  washers  are  merely  circles  stamped  from  sheet-iron,  with  a  hole  punched  through 
the  centre  of  them. 

Nut-locks. — Special  nut-locks  are  not  required  in  trestle-work.  The  method  of  locking 
by  driving  a  nail  close  to  the  side  of  the  nut,  through  a  hole  in  the  washer,  as  mentioned 
when  treating  of  cast  washers,  is  as  good  and  cheap  a  one  as  could  be  desired.  Nicking  the 
threads  of  the  bolts  with  a  centre-punch,  after  the  nuts  have  been  screwed  home,  is  another 
very  good  way.* 

*  This  method  is  used  on  the  Texas  &  Pacific  Railway. 


CHAPTER   VIII. 
CONNECTION  WITH   EMBANKMENT— PROTECTION  AGAINST  ACCIDENTS. 

Connection  with  Embankment. — There  may  be  said  to  be  two  principal  methods  of 
connecting  trestles  with  the  embankment ;  viz.,  by  sills  built  in  the  embankment  itself,  and  by 
a  pile-bent  placed  at  its  edge. 

There  are  several  ways  of  arranging  the  bank-sills.  Sometimes  they  are  piled  up  criss- 
cross, after  the  same  fashion  as  in  building  a  crib,  several  layers  high.  They  should  be  of 
12-in.  X  12-in.  timber,  and  at  least  10  ft.  long,  and  much  better  if  the  crosswise  ones  are 
12  ft.,  securely  fastened  together  by  a  drift-bolt  wherever  they  cross  each  other.  It  is 
seldom  that  more  than  two  sticks  are  used  in  each  layer ;  those  of  the  top  layer  should  be 
at  right  angles  to  the  centre  line  of  the  road,  and  placed  quite  close  together  over  the  centre 
of  the  crib.  Their  upper  surfaces  should  be  on  the  same  grade  level  as  the  caps,  so  that 
the  stringers  will  have  a  good  bearing,  the  stringers  being  securely  drift-bolted  to  them. 
After  everything  is  in  place  earth  should  be  packed  in  closely  both  inside  and  around  the 
crib,  and  the  bank  carried  out  to  at  least  the  middle  of  the  first  bay.  It  will  frequently  be 
found  necessary  to  protect  the  end  of  the  bank  from  being  washed  away  either  by  a  revetment 
of  logs,  by  sheet-piling,  by  rip-rap,  or  by  other  means. 

Rather  than  arrange  the  bank-sills  crib-fashion,  some  prefer  to  lay  from  two  to  eight  or 
more  pieces  of  the  same  size  timber  close  together,  on  the  same  level  and  at  right  angles  to 
the  road.  In  this  case,  as  before,  the  stringers  should  be  drift-bolted  to  the  bank-sills. 

With  whichever  arrangement  is  used,  however,  the  bank  should  be  allowed  to  stand  as 
long  as  possible  before  putting  in  the  bank-sills,  so  that  it  will  have  time  to  settle. 

The  preferable  way  to  connect  the  trestle  with  the  bank  is  by  a  bank-bent.  This  is 
either  a  pile-bent  of  three  or  four  piles,  or  a  light  framed  bent.  In  any  case  the  ends  of  the 
stringers  are  usually  protected  from  contact  with  the  earth  by  a  piece  of  heavy  plank  nailed 
across  them,  called  a  dump-board.  Plate  VI,  Part  II,  shows  a  form  of  bank-bent.  It 
sometimes  happens  that  it  is  necessary  to  plank  up  behind  the  bank-bent  so  as  to  prevent  the 
embankment  spreading  beneath  the  trestle.  In  this  case,  if  a  pile-bent  is  used,  it  should  be 
strongly  built,  and  the  piles  penetrate  to  a  considerable  depth,  especially  if  the  bent  be  of 
any  height.  It  is  also  well  to  brace  the  tops  of  the  piles  against  the  foot  of  the  piles  in  the 
next  bent,  so  as  to  prevent  the  bank-bent  being  forced  over  by  the  pressure  of  the  embank- 
ment behind  it.  If  a  framed  bent  is  chosen,  it  should  be  strong  and  heavy,  and  well  braced 
against  its  neighbor,  both  diagonally  and  by  girts  acting  as  struts.  Tf  possible,  the  girts  or 
horizontal  bracing  should  extend  clear  across  the  whole  structure,  be  of  heavy  material, 
have  butted  joints  and  be  well  fastened,  so  as  to  avoid  buckling;  in  other  words,  they  should 

fulfil  all  of  the  requirements  for  struts. 

52 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


53 


Rerailing    Guards. — All    extensive    and    all    high   trestles   should    be    protected    by   a 
rerailing  guard,  and  it  would  be  far  better  if  all  the  trestles  were,  without  regard  to  their  size. 


Plan  and  Sections  of  Rerailer. 


Elevating  Casting  and  Point. 


Section  oh  G  H. 


Section  ori  E  F. 


Section  on'J  K.- 
FIG.  132. — LATIMER  BRIDGE-GUARD. 

If  this  cannot  be  done,  then  collision-posts  at  least  should  be  erected  to  guard  them.     Even 
where  rerailing  guards  are  used  it  is  an  excellent  plan  to  supplement  them  by  collision-posts 


54 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


arranged  so  as  to  stop  a  car,  the  truck  of  which  has  moved  half  of  the  gauge  or  more  out  of 
line.  This  would  at  least  save  the  bridge,  even  though  it  would  not  prevent  an  accident. 
Fig.  118  shows  such  collision-posts. 

In  Fig.  132,  the  details  of  the  Latimer  bridge-guard,  as  used  on  the  Savannah,  Florida  & 
Western  and  the  Charleston  &  Savannah  Railways,  Mr.  B.  W.  Howe,  Jr.,  Chief  Engineer, 
are  given. 

Refuge-bays. — On  all  trestles  of  any  length,  say  two  hundred  feet  or  over,  refuge-bays 
or  small  railed  platforms  to  receive  workmen  or  track-walkers  who  may  be  caught  on  the 
bridge  by  a  train  should  be  placed  every  two  or  three  hundred  feet  apart.  These  cost  but 
very  little,  and  are  very  efficient  in  insuring  greater  safety  to  employees,  especially  on  single- 
track  trestles. 

Fig.  133  shows  an  excellent  attachment  for  this  purpose. 


- 40- 


*^ 


u 


FIG.  133.  —  REFUGE-BAY. 


Every  fourth  or  fifth  refuge-bay  on  trestles  over  one  thousand  feet  long,  especially  when 
on  or  approached  by  a  curve,  should  be  made  large  enough  to  receive  the  hand-car;  and 
when  the  section-men  or  the  repair-gang  are  at  work  on  the  bridge  they  should  always  be 
compelled  to  place  the  hand-car  on  the  refuge-bay,  together  with  all  idle  tools,  before  they 
begin  work. 

Foot-walks.  —  Some  engineers  recommend  the  laying  of  foot-walks,  composed  of  three 
or  four  rows  of  4-inch  plank,  along  the  centre  of  the  trestle.  This,  however,  for  a  number  of 
reasons,  does  not  seem  desirable,  even  though  it  make  the  life  of  the  track-walker  more 
endurable.  Among  the  objections  may  be  mentioned  : 

1st.  A  tendency  to  make  the  track-walkers  and  others  careless  in  their  examination  of 
the  structure. 

2d.  It  offers  a  greater  temptation  to  people  to  make  a  highway  of  the  trestle  on  account 
of  the  greater  comfort  and  ease  with  which  it  may  be  crossed,  and  hence  encourages  the 
public  to  trespass  upon  the  railroad  company's  property,  and  that  upon  the  most  dangerous 
places. 

3d.  It  increases,  very  largely,  the  area  for  cinders  from  the  engines  to  fall  upon,  and 
hence  makes  the  risk  of  fire  much  greater. 

Fire  Protection.  —  As  long  as  wooden  trestling  is  used  fire  will  be  one  of  the  most 
troublesome  subjects  to  deal  with.  There  are  several  devices,  which  are  now  employed  more 
or  less  extensively,  to  reduce  the  danger  from  this  source. 


./    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  55 

The  one  most  extensively  used  is  to  place  tubs  or  half-barrels,  which  are  kept  full  of 
water,  at  Yhort  intervals  along  the  trestle.  They  should  never  be  over  two  hundred  feet 
apart,  and  should  each  be  supplied  with  a  pail  or  generous-sized  dipper.  The  pails  should 
never  be  made  of  wood,  as  they  are  liable  to  be  found  in  anything  but  a  serviceable  condi- 
tion when  most  needed.  Both  "  Indurated  fibre"  and  "  Granite"  or  enamelled  iron-ware  are 
excellent  materials  for  this  purpose.  The  water  in  the  tubs  should  never  be  allowed  to 
become  low,  and  it  should  be  the  imperative  duty  of  the  track-walker  to  see  that  they  are 
kept  full.  Common  kerosene  oil-barrels  cut  in  half  make  very  good  tubs.  On  single-track 
trestles  these  are  placed  on  one  side  upon  the  ends  of  two  ties,  which  are  purposely  made 
longer  than  the  others  for  this  use.  On  double-track  trestles  they  are  placed  between  the 
two  tracks.  As  this  safeguard  is  very  cheap  indeed,  there  is  no  reason  why  every  trestle  in 
the  country,  without  exception,  should  not  be  so  protected.  In  the  colder  portipns  of  the 
country  there  is,  of  course,  the  disadvantage  of  the  water  freezing  in  winter,  but  this  is  no 
reason  for  depriving  the  public  of  what  little  benefit  there  is  in  the  apparatus  during  the 
balance  of  the  year.  Railroad  companies,  for  their  own  sake,  should  adopt  it,  as  it  would 
frequently  lessen  the  cost  of  an  accident  by  furnishing  immediate  means  for  the  extinguish- 
ment of  many  a  fire  in  its  incipiency,  after  a  wreck  has  occurred. 

A  second  method  is  to  cover  the  stringers  with  a  strip  of  sheet-iron  about  three  or  four 
inches  wider  than  they  are,  before  placing  the  ties,  etc.,  on  them.  See  Plate  III,  Part  II. 
Common  sheet-iron  of  about  No.  27  gauge  is  very  good  for  this  use.  The  iron  should  be 
protected  from  rust  by  some  means.  A  good  preventive  is  common  tar.  Before  putting  the 
iron  in  place  it  should  be  warmed,  and  thoroughly  painted  all  over  with  the  hot  tar. 

A  third  kind  of  fire  protection  is  that  illustrated  in  Plate  VIII,  Part  II,  in  which  the  trestle 
has  a  solid  floor  which  is  covered  with  earth. 

Not  only  should  means  be  provided  to  prevent  the  spread  of  and  to  put  out  fires  that 
have  once  started  from  unavoidable  or  accidental  causes,  but  every  precaution  possible  to 
prevent  them  approaching  from  the  outside  should  also  be  taken.  The  right  of  way  to  a 
width  of  15  to  20  ft.  from  either  side  of  the  trestle  should  be  kept  perfectly  clear  of  all  com- 
bustible matter  of  any  kind  at  all  times.  Not  only  should  this  rule  be  closely  observed,  but 
no  amount  of  any  moment  should  be  allowed  to  accumulate  outride  of  this  limit.  Within  it, 
all  weeds  and  tall  grass  should  be  kept  closely  cut.  When  construction  or  repairs  are  going 
on,  all  chips  and  small  blocks  should  be  raked  up  in  a  heap  at  the  close  of  the  day,  at  a  safe 
distance  from  the  work,  and  set  on  fire.  If  the  work  is  being  done  by  contract,  the  contractor 
ought  to  see  that  this  is  done  for  his  own  protection.  When  the  trestle  is  on  a  line  in  course 
of  construction,  the  right  of  way  should  be  thoroughly  cleared,  the  necessary  space  grubbed, 
and  the  rubbish  cleaned  up  and  completely  burned  before  erection  is  allowed  to  be  begun,  or 
at  any  rate  before  the  trestle  is  accepted  by  the  engineer  or  the  contractor  estimated  for  the 
work  done.  Any  trees  off  of  the  right  of  way  which  are  likely  to  fall  upon  and  injure  the 
trestle  should  be  felled.  It  is  the  railroad  company's  place  to  obtain  permission  to  do  this, 
though  the  contractor  may  be  rightly  called  upon  to  do  the  work  for  which  he  may  be 
estimated  at  the  same  rate  as  for  clearing. 


CHAPTER   IX. 
FIELD    ENGINEERING   AND    ERECTING. 

THERE  are  several  methods  of  laying  out  the  ground  preparatory  to  erecting  a  trestle. 
Of  course  the  exact^  method  of  procedure  will  depend,  to  a  certain  extent,  upon  the  surround- 
ing circumstances. 

The  centre-line  should  be  run  in  carefully  with  a  transit,  and  the  stakes,  which  should  be 
well  made  and  stout,  driven  firmly  into  ground.  A  stake  should  be  placed  on  the  centre-line 
at  each  bent,  and  a  tack,  located  by  the  instrument,  driven  in. 

For  a  pile-trestle  on  land  the  instrument  is  set  up  over  each  centre  stake  and  the  proper 
angle  turned  off,  and  stakes  driven  in  on  either  side  at  the  proper  places  for  the  outside  piles. 
The  tape  is  then  stretched  between  the  centre  and  outside  stakes,  and  stakes  marking  the  posi- 
tion of  the  inside  piles  driven  in.  Some  prefer,  for  framed  bents  especially,  to  use  hubs  in 
place  of  stakes,  and  centre  a  tack  on  each  one.  This,  however,  is  an  unnecessary  refinement. 
For  framed  bents  it  is  preferable  to  place  the  stakes,  which  should  be  driven  down  pretty  close 
to  the  surface  in  this  case,  a  foot  ahead  of  the  centre  of  the  bent.  A  centre  stake  and  one  a 
little  distance  out  on  either  side  is  all  that  is  necessary.  A  mark  is  made  on  the  sill  half-way 
between  the  two  vertical  posts,  and  when  the  bent  is  put  in  position  this  mark  is  placed 
opposite  the  centre  stake.  Care  is  taken  to  see  that  the  sill  sets  back  the  proper  distance 
from  all  of  the  stakes, — 6  in.  between  the  stake  and  the  face  of  the  sill  in  the  case  mentioned. 
Of  course  when  a  framed  bent  has  a  pile-foundation  the  piles  are  located  in  the  same  manner 
as  for  pile-trestles.  When  the  foundation  is  of  masonry  the  centre-line  in  both  directions  is 
first  laid  out  and  then  stakes  driven  in  in  such  a  manner  that  when  strings  are  stretched  between 
them  they  mark  the  outline  of  the  top  of  the  masonry.  A  mark  or  stake  giving  the  elevation 
of  the  top  is  also  given.  After  the  foundation  is  in,  the  centre  is  marked  on  top  of  it. 

For  use  on  this  kind  of  work  a  5<D-foot  tape  is  much  more  convenient  than  a  chain.  An 
ordinary  linen  tape,  so  thoroughly  coated  with  paint  that  it  will  not  stretch  much,  is  accurate 
enough,  though  some  prefer  a  metallic  tape.  A  steel  tape  is  by  no  means  necessary,  as  some 
younger  engineers  are  inclined  to  think,  and  is  very  liable  to  be  broken. 

It  is  exceedingly  convenient  to  have  a  bench-mark,  the  elevation  of  which  is  somewhere 
near  grade,  within  one  or  two  hundred  feet  of  either  end  of  the  trestle,  so  that  it  may  be 
easily  seen  through  the  level  from  the  end  of  the  embankment.  The  elevation  of  the  top  of 
the  bent  can  be  given  with  the  instrument  while  the  bent  is  being  put  in  place,  or  a  bench  can 
be  established  at  the  end  of  the  bank,  and  the  foreman  can  then  obtain  the  elevation  with  an 
ordinary  carpenter's  level  and  straight-edge,  allowance  being  made  by  him  for  the  grade.  In 
the  latter  case  the  work  should  always  be  checked,  every  day  or  so,  with  the  Wye  level. 

After  the  bents  are  completed  and  in  place  the  centre-line  is  to  be  marked  on  each  cap  by 

a  nail  or  tack,  so  that  the  stringers  may  be  placed  in  their  proper  positions.     Track  centres  are 

16 


A    TREATISE   ON    WOODEN    TRESTLE   BRIDGES.  57 

given,  of  course,  in  a  similar  manner  as  on  the  grading,  after  the  ties  have  been  placed  in 
position  and  the  structure  otherwise  completed. 

When  the  trestle  is  over  water  and  on  a  tangent  there  are  several  ways  of  lining  in  the 
piles.  An  instrument  may  be  used,  but  as  a  rule  this  is  not  necessary  unless  the  trestle  is  very 
long.  A  less  expensive  way  is  to  place  very  long  stakes,  standing  four  or  five  feet  out  of  the 
ground,  on  line  with  the  rows  of  piles,  having  two  sets  of  stakes,  one  fifty  or  one  hundred  feet 
behind  the  other,  and  have  the  foreman  line  the  piles  in  with  these.  One  edge  of  the  stakes 
should  be  on  the  line,  of  course,  instead  of  having  the  line  pass  through  them.  The  outside 
stakes  should  also  be  driven  at  the  proper  batter.  As  the  work  progresses  these  stakes  may 
be  replaced  by  narrow  boards  nailed  to  the  piles.  The  results  should  be  checked  by  the  en- 
gineer in  charge,  from  time  to  time. 

Erecting. — The  method  used  in  erection  depends  upon  the  location.  Where  it  is  per- 
missible the  bents  are  generally  framed  together  while  lying  upon  the  ground,  with  the  sill  so 
placed  that  when  the  bent  is  raised  it  will  be  in  its  proper  position.  They  are  raised,  usually 
by  blocks  and  a  fall,  the  rope  being  drawn  in  by  a  horse-power  or  steam  hoisting-engine 
or  by  a  gang  of  men.  As  soon  as  the  bents  have  reached  the  upright  position  they  are 
fastened  to  those  already  erected  by  temporary  bracing,  which  should  be  supplemented  by  the 
permanent  longitudinal  bracing  as  rapidly  as  possible,  if  such  is  to  be  used.  If  not,  then  the 
stringers  should  be  placed  in  position.  Stay-ropes  should  be  attached  to  the  bent  before  it  is 
raised,  so  that  when  it  reaches  its  upright  position  it  cannot  be  pulled  over.  Of  course  when 
the  bents  are  of  any  considerable  height  they  are  liable  to  considerable  racking  if  erected  in 
this  manner.  Attaching  an  additional  fall  to  a  couple  of  timbers  lashed  to  the  bent  about 
half-way  up,  one  timber  on  either  side,  tends  to  prevent  this  to  a  considerable  extent.  How- 
ever, great  care  must  be  taken  to  draw  in  the  ropes  of  the  two  falls  at  the  proper  rates.  It  is 
in  this  part  of  the  work  of  building  high  trestles  that  the  third  class  of  high-trestle  structures 
proves  so  convenient.  The  lowest  deck  is  erected  and  the  purlins  placed  upon  it.  Then  the 
timbers  for  the  bents  of  the  next  deck  are  put  together  on  a  temporary  staging  formed  by 
placing  a  flooring  on  the  purlins.  These  bents  are  then  erected  the  same  as  though  they  were 
upon  the  ground,  the  purlins  put  on  top  of  them,  and  the  same  process  carried  on  as  before 
until  the  full  height  is  reached.  Then  there  is  less  liability  to  injury  or  loss,  while  in  the 
course  of  erection,  through  the  bents  falling  from  lack  of  temporary  bracing,  as  is  too  fre- 
quently the  case. 

Another  method  is  to  complete  the  work  and  lay  the  track  as  rapidly  as  the  bents  are 
placed.  The  bents,  in  this  case,  may  either  all  be  framed  at  any  convenient  place,  or  on  the 
ground  as  before,  and  then  brought  to  and  placed  in  position  or  raised  by  a  derrick  and  hoist- 
ing machine  placed  on  a  flat  car.  The  boom  of  the  derrick  should,  as  a  rule,  be  long  enough 
to  reach  out  so  as  to  place  the  second  bent  beyond  the  completed  work  in  position.  The 
bents  for  a  trestle  much  over  15  ft.  high  could  not,  of  course,  be  conveniently  carried  any  dis- 
tance. 

Sometimes  the  bents  are  built  in  place.  This  method  is  absolutely  necessary  for  very 
high  structures,  unless  they  arc  of  the  type  of  class  three.  The  cost  is  generally  greater  than 
with  the  previous  methods.  One  of  the  strong  arguments  advanced  for  both  cluster-bent  and 
compound  timber  trestles  is  the  economy  with  which  they  may  be  erected  by  this  method. 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


On  account  of  the  smaller  size  of  the  timbers  they  may  be  handled  with  much  greater  ease 
and  rapidity. 

TOOLS. 

The  following  is  a  description  of  the  tools  used  by  the  carpenters  in  trestle-building.     Most 
of  them  will  be  found  absolutely  indispensable;  the  remainder  greatly  facilitate  the  work: 


FIG.  134. — SPIKE-MAUL. 


FIG.  135. — MALLET. 


Fig. 


Hammers.  —  Practically  the  only  hammers  used  to  any  extent  are  the  spike-mauls. 
134  gives  the  details  of  a  good  maul. 

Mallets.  —  Mallets  are  merely  wooden  hammers.  They  are  used  principally  to  drive  the 
chisels  into  the  wood.  Being  of  wood,  they  do  not,  of  course,  injure  the  handles  of  the 
chisels  as  steel  hammers  would.  They  are  made  either  of  a  wood  called  lignum  vitae  or  of 
hickory.  The  former  is  more  durable,  and  also  more  costly.  Fig.  135  shows  one  form  of 
mallet  very  commonly  used. 

Saws.  —  A  cross-cut  saw,  such  as  is 
shown  in  Fig.  136,  about  five  feet  long, 
is  exceedingly  useful.  If  enough  work 
is  laid  out  beforehand,  so  that  two 


"~'VVW7/W^^  men  can  be  assigned  to  the  saw  and  be 

FIG.  136.— CROSS-CUT  SAW.  kept  constantly  employed,  great  econ- 

omy will  result.  If  the  men  have  to  stop  between  cuts  to  lay  out  the  work  themselves,  more 
or  less  time  is  lost  in  making  the  change  and  hunting  for  the  tools,  and  it  often  happens  that 
one  man  remains  entirely  idle  while  the  other  is  preparing  the  work. 

Hand  cross-cut  saws  are  also  required  (Fig. 
137).  These  should  be  of  the  heavier  patterns, 
and  the  blade  at  least  two  feet  long.  If  the 
handle  is  bound  with  brass  and  at  right  angles 
to  the  back,  so  that  the  saw  may  be  used  as  a 
square,  it  will  be  found  to  be  very  convenient. 
These  saws  are  used  for  the  lighter  parts  of  the  work,  such  as  notching  the  ties,  guard-rails, 
ends  of  stringers,  etc. 

In  addition  to  these  it  will  be  necessary  to  have  some  rip-saws.  These  are  used  for  saw- 
ing with  the  grain  of  the  wood,  and  are  about  the  same  size  as  hand  cross-cut  saws,  or  a  little 
larger.  The  teeth  are  larger  and  differently  shaped  than  those  of  the  cross-cut  saw. 

Boring-machines. — For  boring  out  mortises  preparatory  to  finishing  with  the  chisel,  a 
boring-machine  is  exceedingly  economical  and  useful. 


FIG.  137. — HAND-SAW. 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


59 


Ship  Augers. — For  boring  holes  for  bolts,  drift-bolts,  lag-screws,  etc.,  a  ship  auger,  such 
as  is  shown  in  Fig.  138,  is  most  commonly  used.  Augers  of  this  style  should  be  long  enough 
to  enable  a  man  to  use  them  standing  without  having  to  stoop. 


A 


FIG.  141.— BROADAXE. 


FIGS.  139,  140. — AXES. 


FIG.  138. — SHIP  AUGER. 


FIG.  142. — HATCHET. 


Axes. — A  common  long-handle  axe  (Figs.  139  and  140)  is  very  useful.  They  are  made  of 
different  weights;  usually,  each  man  has  his  own  particular  liking  in  this  regard.  About  4  Ibs. 
is  a  good  weight  for  the  head,  exclusive  of  the  helve.  A  5-lb.  axe  is  rather  heavy,  while  one 
weighing  only  3  Ibs.  is  rather  light. 

In  addition  to  the  common  axe,  broadaxes  (Fig.  141)  and  hatchets  (Fig.  142)  are  found 
convenient. 

Adzes. — An  adze  may  be  denned  as  an  axe  with  the  cutting  edge  set  at  right  angles  to 
the  handle.  This  tool,  which  is  absolutely  necessary  to  economical  and  rapid  work,  is  shown 
in  Fig.  143. 


FIG.  143. — ADZE. 


FIG.  144. — FRAMING  CHISEL. 


Chisels. — The  best  form  of  chisels  for  this  kind  of  work  is  the  firmer  or  framing  chisel 
(Fig.  144).  The  handle  should  be  held  in  a  socket  forged  on  the  upper  end  of  the  blade,  and 
should  have  its  top  end  protected  by  an  iron  ring.  The  most  convenient  widths  are  if  in. 
and  2  in. 

They  are  used  to  cut  out  mortises,  and  the  notches  in  the  ties,  guard-rails,  etc.  Tanged 
chisels  are  of  no  use,  as  the  work  is  too  heavy  for  them. 

Squares  and  Rules. — The  ordinary  steel  framing  square,  made  of  sheet  steel  about  \  in. 
thick,  and  with  one  arm  about  two  feet  and  the  other  about  twelve  inches  long,  in  addition  to 


60  A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 

a  batter  template,  such  as  is  shown  in  Fig.  45,  is  all  that  is  required  in  this  line.  The  arms 
should  be  graduated  in  inches  and  quarter-inches. 

Besides  the  common  two-foot  rule,  it  greatly  facilitates  matters  to  have  a  strip  of  board 
about  £  in.  thick  by  2^  in.  wide  and  10  ft.  long,  divided  into  feet  and  numbered  both  ways,  one 
set  of  numbers  being  in  red  and  the  other  in  black,  and  separated  from  each  other  by  a  line 
through  the  centre  of  the  stick.  The  first  foot  of  either  set  should  be  divided  into  inches  and 
quarters  of  an  inch. 

Cant-hooks  and  Lug-hooks. — Both  cant  and  lug  hooks  will  be  found  necessary  and 
useful  in  handling  the  timber.  Fig.  145  shows  a  cant-hook  and  Fig.  146  a  modification  of  a 


FIG.  145. — CANT-HOOK.  FIG.  146. — PEAVEY.  FIG.  147. — LUG-HOOK. 

cant-hook  called  a  peavey.     A  lug-hook  is  shown  in  Fig.  147. 

Log-wheels. — A  pair  of  log- wheels  will  be  found  very  useful  for  carrying  the  timber  from 
one  place  to  another.  They  are  merely  two  strongly-built  wheels,  of  a  large  diameter,  with  a 
broad,  heavy  tire,  united  by  a  very  strong  axle.  To  the  axle  is  attached  a  shaft,  so  that  a 
team  of  horses  or  yoke  of  oxen  may  be  hitched  to  the  wheels.  The  wheels  are  backed  over 
one  end  of  a  timber  to  be  moved,  and  the  end  raised  from  the  ground  by  means  of  chains  and 
an  arrangement  of  levers.  The  rear  end  of  the  stick  is  allowed  to  drag  upon  the  ground. 

Wrenches. — For  trestle-building,  the  ordinary  monkey-wrench  is  of  little  use.  As  the 
nuts  are  all  of  one  or  two  sizes,  the  form  shown  in  Fig.  148  is  one  of  the  most  convenient. 


FIG.  148. — WRENCH. 

Another  form  in  common  use  is  made  upon  the  same  principle  as  a  clock  key.  This 
enables  the  men  to  tighten  up  many  of  the  nuts  without  stooping. 

Hoisting-machines. — Under  the  head  of  ERECTION,  hoisting-machines  were  spoken  of  as 
being  used  to  aid  in  raising  the  bents  and  timbers.  Whether  horse  or  steam  power  machines 
are  used  will  depend  on  several  conditions,  among  which  may  be  mentioned  the  extent  of  the 
work  and  the  means  for  the  transportation  of  the  machine  to  the  site.  A  horse-power 
machine  can  be  much  more  easily  transported,  and  can  be  carried  over  roads  over  which  it 
would  be  either  impossible  to  transport  a  steam  machine  or  prohibitory  in  cost.  Work 
cannot  be  prosecuted  as  rapidly,  of  course,  with  a  horse-power  as  with  a  steam  machine. 

Saw-mills. — It  sometimes  happens  that  a  very  extensive  piece  of  trestling  will  be 
needed  in  a  location  where  there  is  plenty  of  timber,  but  no  saw-mills  at  hand.  In  this  case, 
if  it  is  deemed  necessary  to  use  sawn  timber,  a  portable  saw-mill  will  be  found  very 
convenient.  These  mills  are  generally  arranged  so  that  they  can  be  very  conveniently  and 
easily  moved  from  place  to  place,  and  may  be  obtained  of  various  capacities. 


CHAPTER   X. 
PRESERVATION   OF  JOINTS   AND   STANDARD   SPECIFICATIONS. 

Preservation  of  Joints. — Wherever  two  surfaces  of  timber  touch,  they  should  always 
be  painted  with  some  preservative  material.  White-lead  is  sometimes  used,  but  is  rather 
costly.  Common  tar  heated  very  hot,  coal-tar,  and  creosote  oil  are  excellent  for  this  purpose, 
while  they  also  have  the  advantage  of  cheapness.  Of  course,  if  all  of  the  timber  could  be 
treated  with  a  preservative  agent  so  much  the  better;  but  this  is  generally  too  expensive. 
Creosoted  timber  is  probably  as  durable  as  that  preserved  by  any  other  process.  This  subject 
of  timbei  preservation,  however,  will  not  be  treated  of  in  this  work.  Those  who  may  wish  to 
know  more  about  the  subject  are  referred  to  the  various  books  and  papers  on  the  subject.* 

Standard  Specifications. — The  degree  of  care  used,  and  the  completeness  of  the 
specifications  drawn  up  by  different  roads,  varies  between  exceedingly  wide  limits.  Some  say 
almost  nothing  on  the  subject  at  all,  only,  perhaps,  devoting  one  or  two  lines  in  the  General 
Specifications  to  the  subject ;  others  draw  up  a  special  set  entirely  devoted  to  the  subject. 

The  following  set  of  specifications  were  compiled  from  the  best  parts  of  the  best 
standards  in  use  that  could  be  obtained.  The  paragraphs  having  the  same  headings  are 
alternative  paragraphs,  any  one  of  which  may  be  used  to  suit  the  special  conditions  of 
the  road. 

STANDARD   SPECIFICATIONS   FOR   WOODEN   TRESTLES.f 

CLEARING. 

Before  commmencing  work  on  any  Structure,  the  ground  must  be  entirely  cleared  of  logs, 
brush,  and  trees  for  the  entire  width  of  the  right  of  way.  All  material  of  a  combustible 
nature  must  be  placed  in  piles  at  convenient  places,  and  completely  burned. 

*  Short  and  interesting  articles  on  this  subject  appeared  in  the  Railroad  Gazette  of  Sept.  5,  1890,  and 
Sept.  19,  1890. 

f  The  form  used  on  the  Cincinnati,  New  Orleans  &  Texas  Pacific  Ry.  and  associate  roads  (Cincinnati 
Southern  Ry.,  Alabama  Great  Southern  R.  R.,  New  Orleans  &  North-Eastern  R.  R.,  Vicksburg  &  Meridian 
R.  R.,  Vicksburg,  Shreveport  &  Pacific  R.  R.),  G.  B.  Nicholson,  Chief  Engineer,  has  been  very  closely 
followed.  The  specifications  of  the  following  roads  have  also  been  drawn  from : 

Central  Railroad  &  Banking  Co.  of  Georgia,  V.  H.  Kriegshaber,  Asst.  Engineer. 

Ohio  Connecting  Ry.,  M.  J.  Becker,  Chief  Engineer. 

Georgia  Pacific  Ry.  Co.,  I.  Y.  Sage,  General  Superintendent. 

Cleveland,  Akron  &  Columbus  Ry.  Co. 

Gulf,  Colorado  &  Santa  Fe  Ry.  Co.,  B.  F.  Booker,  Asst.  Engineer. 

St.  Paul,  Minneapolis  &  Manitoba  Ry.  Co.,  N.  D.  Miller,  Chief  Engineer. 

Florence  R.  R.,  F.  Gardner,  Chief  Engineer. 

Brantford,  Waterloo  &  Lake  Erie  R.  R. 

Specifications  for  Standard  Pile  and  Timber  Trestle  Bridging, — Eng,  News. 

French  Broad  Valley  R.  R.,  H.  M.  Ramseur,  Chief  Engineer. 

6z 


62  A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 

Dangerous  trees,  liable  to  fall  on  the  trestle,  when  outside  the  right  of  way,  must  be 
felled  by  the  contractor;  it  being  understood  that  the  railroad  company  is  to  obtain 
permission  from  the  land-owner. 

Such  portion  of  the  right  of  way,  as  may  be  deemed  necessary  by  the  engineer,  shall  be 
grubbed. 

DRAWINGS. 

The  drawings  are  to  the  scale  indicated  and  marked  ;  but  in  all  cases  the  figures  are  to 
be  taken,  and  in  case  of  omission  the  engineer  in  charge  is  to  be  referred  to  for  dimensions. 
Under  no  circumstances  are  the  drawings  to  be  scaled  either  by  the  contractor  or  by  any  of 
his  men.  The  Engineer  will  be  required  to  mark  the  dimensions  upon  the  contractor's  blue 
print,  and  to  keep  a  record  of  the  same  in  his  office. 

DIMENSIONS. 

All  posts,  braces,  clamps,  stringers,  packing-blocks,  ties,  guard-timbers,  sills,  and  all  tim- 
ber generally,  will  be  of  the  exact  dimensions  given  and  figured  upon  the  plan.  Variations 
from  these  will  only  be  allowed  upon  the  written  consent  of  the  engineer  in  charge. 

TIMBER. 

All  timber  shall  be  of  good  quality  and  of  such  kinds  as  the  engineer  may  direct,  free 
from  wind-shakes,  wanes,  black,  loose,  or  unsound  knots,  worm-holes,  and  all  descriptions  of 
decay.  It  must  be  sawed  true  and  out  of  wind,  and  full  size.  Under  no  circumstances  will 
any  timber  cut  from  dead  logs  be  allowed  to  be  placed  in  any  portion  of  the  structure :  it 
must  in  every  case  be  cut  from  living  trees. 

PILES. 

Piles  shall  be  of  good  live 

They  will  be  either  round  of  square,  as  may  be  required  by  the  engineer. 

Round  piles  must  be  straight,  and  have  all  the  bark  peeled  off.  They  must  have  at  least 
twelve  (12)  inches  diameter  of  heart  at  the  cut-off,  when  cut  to  grade  to  receive  the  cap.  The 
smaller  end  must  be  at  least  eight  inches  in  diameter. 

Square  piles  must  be  hewn  (or  sawed)  twelve  (12)  inches  square.  Each  pile  must  have  at 
least  nine  (9)  inches  of  heart  wood  on  each  face,  from  the  head  of  the  pile,  after  being  cut  to 
grade,  to  five  feet  below  the  surface  of  the  ground  in  which  the  pile  is  driven. 

All  piles  must  be  properly  pointed.  They  shall,  if  required,  be  shod  with  cast  or  wrought 
iron  shoes,  made  according  to  the  plan  furnished  by  the  engineer.  In  driving  they  shall  be 
capped  with  suitable  wrought-iron  rings,  if  necessary,  to  prevent  splitting.  The  actual  cost, 
delivered  on  the  ground,  of  the  necessary  shoes  and  rings  will  be  allowed  the  contractor. 

They  must  be  driven  to  hard  bottom,  or  until  they  do  not  sink  more  than  five  inches  under 
the  last  five  (5)  blows  by  a  hammer  of  at  least  2000  Ibs.  weight  falling  twenty-five  (25)  feet. 
A  heavier  hammer  with  a  shorter  fall  is  preferred. 

All  piles  injured  in  driving,  or  driven  out  of  place,  shall  either  be  cut  off  or  withdrawn, 
as  the  engineer  may  elect,  and  another  one  driven  in  its  stead.  The  pile  thus  replaced  will 
not  be  paid  for. 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES.  63 

All  piles  under  track-stringers  must  be  accurately  spaced  and  driven  vertically,  and  in  each 
bent  the  batter-piles  will  be  driven  at  the  angle  shown. 

Piles  shall  be  measured  by  the  lineal  foot  after  they  are  driven  and  cut  off,  and  the  price 
per  lineal  foot  shall  be  understood  to  cover  the  expenses  of  transportation,  driving,  cutting 
off,  removing  the  bark,  and  all  labor  and  materials  required  in  the  performance  of  the  work, 
but  that  portion  of  each  pile  cut  off  shall  be  estimated  and  paid  for  by  the  lineal  foot  as 
"  Piles  cut  off." 

The  contractor  must  give  all  facilities  in  his  power  to  aid  the  pile-recorder  in  his 
duties. 

Parts  of  pile-heads  projecting  beyond  the  cap  must  be  adzed  off  to  a  slope  of  45  degrees. 


FRAMING. 

All  framing  must  be  done  to  a  close  fit,  and  in  a  thorough  and  workmanlike  manner. 
No  blocking  or  shimings  of  any  kind  will  be  allowed  in  making  joints,  nor  will  open  joints 
be  accepted. 

All  joints,  ends  of  posts,  piles,  etc.,  and  all  surfaces  of  wood  on  wood  shall  be  thoroughly 
.hot  creosote-oil  and  covered  with  a  coat  of  hot  asphaltum, 
hot  asphaltum, 
painted  with  1   hot  common  tar, 

a  good  thick  coat  of  pure  white-lead  ground  in  and  mixed  with 
pure  linseed-oil. 


All  bolt  and  other  holes  bored  in  any  part  of  the  work  must  be  thoroughly  saturated  with 

f  hot  creosote-oil, 

hot  asphaltum,  And  all  bolts  and 

drift-bolts  before 
being  put  in  place 
must  be 


hot  tar, 
coal-tar, 

white-lead  mixed  with 
linseed-oil. 


warmed  and  coated  with  hot  creosote-oil, 
warmed  and  coated  with  hot  asphaltum, 
warmed  and  coated  with  hot  tar, 
coated  with  coal-tar, 
coated  with  white-lead  and  linseed-oil. 


All  bolt-holes  for  bolts  three  quarters  (£)  of  an  inch  in  diameter  or  over  must  be  bored 
with  an  auger  one  eighth  (•§• )  of  an  inch  smaller  in  diameter  than  the  bolt,  in  order  to  secure  a 
perfectly  tight  fit  of  the  bolt  in  the  hole.  For  bolts  five  eighths  (f)  of  an  inch  in  diameter  or 
smaller  the  auger  must  be  one  sixteenth  (y1^)  of  an  inch  smaller  for  the  same  reason. 


TRESTLES   ON   CURVES. 


Where  any  trestle-bridge  is  built  on  a  curve  the  blocking  for  the  elevation  of  the  outer 
rail,  or  other  means  for  elevating  the  outer  rail,  will  be  as  per  standard  drawings  for  the  same, 
a  copy  of  which  will  be  furnished  from  the  Chief  Engineer's  office. 


*  Alternative  methods  of  treatment. 


64  A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 

CREOSOTED   TRESTLES. 

All  piles  used  in  creosoted  trestles  must  have  the  bark  peeled  off,  and  be  pointed,  before 
treatment.  None  of  the  sap  wood  must  be  hewn  from  the  piles.  No  notching  or  cutting  of 
the  piles  will  be  allowed  after  treatment,  except  the  sawing  off  of  the  head  of  the  pile  to  the 
proper  level  for  the  reception  of  the  cap,  and  the  levelling  of  such  part  of  the  head  as  may 
project  from  under  the  cap. 

The  heads  of  all  creosoted  piles,  after  the  necessary  cutting  and  trimming  has  been  done 
to  receive  the  cap,  must  be  saturated  with  hot-creosote  oil,  and  then  covered  with  hot  asphal- 
tum  before  putting  the  caps  in  place. 

Timber  in  creosoted  trestles  must  be  cut  and  framed  to  the  proper  dimensions  before 
treatment.  No  cutting  or  trimming  of  any  kind  will  be  allowed  after  treatment,  except  the 
boring  of  the  necessary  bolt-holes. 

Hot  creosote-oil  must  be  poured  into  the  bolt-holes  before  the  insertion  of  the  bolts, 
in  such  a  manner  that  the  entire  surface  of  the  holes  shall  receive  a  coating  of  creosote-oil. 

TREATMENT   OF   CREOSOTED   TILES  AND   TIMBER. 

All  creosoted  timber  and  piles  shall  be  prepared  in  accordance  with  the  following  process : 
The  timber  and  piles,  after  having  been  cut  and  trimmed  to  the  proper  length,  size,  and 
shape,  shall  be  submitted  to  a  contact  steaming  inside  the  injection-cylinders,  which  shall  last 
from  two  to  three  hours,  according  to  the  size  of  the  timbers  ;  then  to  a  heat  not  to  exceed 
230°,  F.,  in  a  vacuum  of  twenty-four  (24)  inches  of  mercury,  for  a  period  long  enough  to  thor- 
oughly dry  the  wood.  The  creosote-oil,  heated  to  a  temperature  of  about  1/5°,  shall  then  be 
let  in  the  injection-cylinder  and  forced  into  the  wood  under  a  pressure  of  150  pounds  per 
square  inch,  until  not  less  than  fifteen  (15)  pounds  of  oil  to  the  cubic  foot  of  wood  has  been 
absorbed. 

The  oil  must  contain  at  least  ten  (10)  per  cent  of  carbolic  and  cresylic  acids,  and  have  at 
least  twelve  (12)  per  cent  of  naphthaline. 

IRON. 

Wrou^ht-iron. — All  wrought-iron  must  be  of  the  best  quality  of  American  refined  iron, 
tough,  ductile,  uniform  in  quality,  and  must  have  a  limit  of  elasticity  of  not  less  than  twenty 
six  thousand  (26,000)  pounds  per  square  inch. 

All  bolts  must  be  perfect  in  every  respect,  and  have  nuts  and  screws  to  the  full  standard 
sizes  due  to  their  diameters.  The  thickness  of  the  nut  shall  not  be  less  than  the  diameter  of 
the  bolts  and  the  size  of  its  square  not  less  than  twice  the  diameter  of  the  bolt. 

{square  \ 

countersunk     >  heads, 
round   button  ) 
with  a  thickness  not  less  than  the  diameter  of  the  bolt,  and  the  size  of  its  square  not  less  than 

twice  the  diameter  of  the  bolt, 
with  a  thickness  at  the  centre  of  not  less  than  three  quarters  of  the  diameter  of  the  bolt,  and 

an  extreme  diameter  of  not  less  than  two  and  one  half  times  the  diameter  of  the  bolt, 
countersunk  on   the   under  side  so  as  to   fit  into  a  cup-washer,  with  an  extreme  diameter 
of  not  less  than  twice  the  diameter  of  the  bolt. 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES.  65 

Cast-iron. — All  castings  must  be  from  good,  tough  metal,  of  a  quality  capable  of  bearing 
a  weight  of  five  hundred  and  fifty  (550)  pounds,  suspended  at  the  centre  of  a  bar  one  (i)  inch 
square,  four  and  one  half  (4!)  feet  between  supports.  They  must  be  smooth,  well-shaped, 
free  from  air-holes,  cracks,  cinders,  and  other  imperfections. 

All  iron,  before  leaving  the  shop  must  be  thoroughly  soaked  in  boiled  linseed-oil. 

INSPECTION  AND  ACCEPTANCE. 

All  materials  will  be  subject  to  the  inspection  and  acceptance  of  the  Engineer  before 
being  used.  The  Contractor  must  give  all  proper  facilities  for  making  such  inspection  thorough. 

Any  omission  to  disapprove  of  the  work,  by  the  Engineer,  at  the  time  of  a  monthly  or 
other  estimate  being  made,  shall  not  be  construed  as  an  acceptance  of  any  defective  work. 

PROTECTION  AGAINST   FIRE. 

The  Contractor  must  each  evening,  before  quitting  work,  remove  all  shavings,  borings, 
and  scraps  of  wood  from  the  deck  of  the  trestle,  and  from  proximity  to  the  bents  or  piles, 
and  on  the  completion  of  the  work  must  take  down  all  staging  used  in  the  erection,  and  burn 
all  shavings,  chips,  etc.,  and  remove  all  pieces  of  timber  to  a  distance  sufficient  to  insure 
safety  from  fire. 

ROADS   AND   HIGHWAYS. 

Commodious  passing  places  for  public  and  private  roads  shall  be  kept  in  good  condition 
by  the  Contractor,  and  he  shall  open  and  maintain  thereafter  a  good  and  safe  road  for 
passage  on  horseback  along  the  whole  length  of  his  work. 

RUNNING   OF  TRAINS.* 

The  Contractor  shall  so  conduct  all  his  operations  as  not  to  impede  the  running  of  trains 
or  the  operation  of  the  road.  He  will  be  responsible  to  the  Railroad  Company  for  all 
injuries  to  rolling-stock  or  damage  from  wrecks  caused  by  his  negligence.  The  cost  of  such 
damage  will  be  retained  from  his  monthly  and  final  estimates. 

RISKS. 

The  Contractor  shall  assume  all  risks  from  floods,  storms,  and  casualties  of  every  descrip- 
tion, except  those  caused  by  the  Railroad  Company,  until  the  final  acceptance  of  the  work. 

LABOR   AND    MATERIAL. 

The  Contractor  must  furnish  all  material  and  labor  incidental  to  or  in  any  way  connected 
with  the  manufacture,  transportation,  erection,  and  maintenance  of  the  structure  until  its  final 
acceptance. 

Disorderly,  quarrelsome,  or  incompetent  men  in  the  employ  of  the  Contractor,  or  those 
who  persist  in  doing  bad  work  in  disregard  of  these  specifications,  must  be  discharged  by  the 
Contractor  when  requested  to  do  so  by  the  Engineer. 

*  This  clause  may  be  inserted  when  the  repairs  or  renewals  are  made  by  contract,  or  on  the  double- 
tracking  of  a  road. 


66  A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 

Whenever  the  Chief  Engineer  may  deem  it  advisable,  he  may  name  the  rates  and  prices 
to  be  paid  by  the  Contractors,  for  such  time  as  he  may  designate,  to  the  several  classes  of 
laborers  and  mechanics  in  their  employ,  and  for  the  hire  of  horses,  mules,  teams,  etc.,  and 
these  shall  not  be  exceeded ;  and  having  given  due  notice  to  the  Contractors  of  his  action  in 
regard  to  these  matters,  they  shall  be  bound  to  obey  his  orders  in  relation  thereto.  The 
Chief  Engineer  shall  not,  however,  name  a  rate  or  price  for  any  class  of  labor,  etc.,  higher 
than  the  maximum  rates  being  paid  by  the  Contractor  paying  the  highest  for  that  class. 

INTOXICATING   LIQUORS. 

Contractors  will  not  themselves,  nor  by  their  agents,  give  nor  sell  any  intoxicating 
liquors  to  their  workmen,  or  any  persons  at  or  near  the  line  of  the  railway,  nor  allow  any 
to  be  brought  on  the  works  by  the  laborers  or  any  other  person,  and  will  do  all  in  their  power 
to  discountenance  their  use  in  the  vicinity  of  the  work  by  persons  in  their  employ.  A 
continued  disregard  for  this  clause  will,  if  deemed  necessary  by  the  Engineer,  be  considered 
as  a  good  and  sufficient  reason  for  declaring  the  contract  forfeited. 

DAMAGES   AND   TRESPASS. 

Contractors  shall  be  liable  for  all  damages  to  landholders,  arising  from  loss  or  injury  to 
crops  or  cattle,  sustained  by  any  cause  or  thing  connected  with  the  works,  or  through  any 
of  their  agents  or  workmen.  They  will  not  allow  any  person  in  their  employ  to  commit 
trespass  on  the  premises  of  persons  in  the  vicinity  of  the  works,  and  will  forthwith,  at  the 
request  of  the  Engineer,  discharge  from  their  employ  any  that  may  be  guilty  of  committing 
damage  in  this  respect.  They  will  also  maintain  any  fences  that  may  be  necessary  for  the 
proper  protection  of  any  property  or  crops. 

REMOVAL  OF  DEFECTIVE  WORK. 

The  Contractors  will  remove  at  their  own  expense  any  material  disapproved  by  the 
Engineer;  and  will  remove  and  rebuild,  without  extra  charge,  and  within  such  time  as  may 
be  fixed  by  the  Engineer,  any  work  appearing  to  the  Engineer,  during  the  progress  of  the 
work  or  after  its  completion,  to  be  unsoundly  or  improperly  executed,  notwithstanding 
that  any  certificate  may  have  been  issued  as  due  to  the  execution  of  the  same.  The 
Engineer  shall,  however,  give  notice  of  defective  work  to  the  Contractors  as  soon  as  he  shall 
become  cognizant  of  the  same.  On  default  of  the  Contractors  to  replace  the  work  as  directed 
by  the  Engineer,  such  work  may  be  done  by  the  Railroad  Company  at  the  Contractors' 
expense. 

DELAYS. 

No  charge  shall  be  made  by  the  Contractor  for  hindrances  and  delay,  from  any  cause,  in 
the  progress  of  any  portion  of  his  work ;  but  it  may  entitle  him  to  an  extension  of  the  time 
allowed  for  completing  the  work  sufficient  to  compensate  for  the  detention,  to  be  determined 
by  the  Engineer,  provided  he  shall  give  the  Engineer  in  charge  immediate  notice,  in  writing, 
of  the  detention. 

EXTRA   WORK. 

No  claim  shall  be  allowed  for  extra  work  unless  done  in  pursuance  of  a  written  order 
from  the  Engineer,  and  the  claim  made  at  the  first  estimate  after  the  work  was  executed, 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  67 

unless  the  Chief  Engineer,  at  his  discretion,  should  direct  the  claim,  or  such  part  of  it  as  he 
may  deem  just  and  equitable,  to  be  allowed, 

Unless  a  price  is  specified  in  the  contract  for  the  class  of  work  performed,  extra  work 
will  be  paid  for  at  the  actual  cost  of  the  material  remaining  in  the  structure  after  its  com- 
pletion and  the  cost  of  the  labor  for  executing  the  work,  plus  fifteen  (15)  per  cent  of  this 
total.  This  fifteen  (15)  per  cent  will  be  understood  to  include  the  use  of  and  cost  of  all  tools 
and  temporary  structures,  staging,  etc.,  and  the  Contractor's  profit,  and  no  extra  allowance 
over  and  above  this  will  be  made. 

INFORMATION  AND  FORCE  ACCOUNTS. 

The  Contractor  will  aid  the  Engineer  in  every  way  possible  in  obtaining  information,  and 
freely  furnish  any  which  he  may  possess,  by  access  to  his  books  and  accounts,  in  regard  to 
the  cost  of  work,  labor,  time,  material,  force  account,  and  such  other  items  as  the  Engineer 
may  require  for  the  proper  execution  of  the  work,  and  shall  make  such  reports  to  him  from 
time  to  time  as  he  may  deem  necessary  and  expedient. 

PROSECUTION  OF  THE  WORK. 

The  Contractor  shall  commence  his  work  at  such  points  as  the  Engineer  may  direct,  and 
shall  conform  to  his  directions  as  to  the  order  of  time  in  which  different  parts  of  the  work 
shall  be  done,  as  well  as  the  force  required  to  complete  the  work  at  the  time  specified  in  the 
contract.  In  case  the  Contractor  shall  refuse  or  neglect  to  obey  the  orders  of  the  Engineer  in 
the  above  respects,  then  the  Engineer  shall  have  power  to  either  declare  the  contract  null  and 
void  and  relet  the  work,  or  to  hire  such  force  and  buy  such  tools  at  the  Contractor's  expense 
as  may  be  necessary  for  the  proper  conduct  of  the  work,  as  may  in  his  judgment  be  to  the  best 
interests  of  the  Railroad  Company. 

CHANGES. 

At  any  time  during  the  execution  or  before  the  commencement  of  the  work  the  Engineer 
shall  be  at  liberty  to  make  such  changes  as  he  may  deem  necessary,  whether  the  quantities  are 
increased  or  diminished  by  such  changes,  and  the  Contractor  shall  be  entitled  to  no  claim  on 
account  of  such  changes  beyond  the  actual  amount  of  the  work  done  according  to  these  speci- 
fications at  the  prices  stipulated  in  the  contract,  unless  such  work  is  made  more  expensive  to 
him,  when  such  rates  as  may  be  deemed  just  and  equitable  by  the  Chief  Engineer  will  be  al- 
lowed him  ;  if,  on  the  other  hand,  the  work  is  made  less  expensive,  a  corresponding  deduction 
may  be  made. 

QUANTITIES. 

It  is  distinctly  understood  that  the  quantities  of  work  estimated  are  approximate,  and 
the  Railroad  Company  reserves  the  right  of  having  built  only  such  kinds  and  quantities,  and 
according  to  such  plans,  as  the  nature  or  economy  of  the  work  may,  in  the  opinion  of  the 
Engineer,  require. 

ENGINEER. 

The  term  Engineer  will  be  understood  to  mean  the  Chief  Engineer,  or  any  of  his  author- 
ized Assistants  or  Inspectors,  and  all  directions  given  by  them,  under  his  authority,  shall  be 


68  A    TREATISE   ON    WOODEN   TRESTLE   JBRIDGES. 

fully  and  implicitly  followed,  carried  out,  and  obeyed  by  the  Contractor  and  his  agents  and 
employees. 

PRICE   AND   PAYMENT. 

The  prices  bid  will  include  the  furnishing  of  materials,  tools,  scaffolding,  watching,  and  all 
other  items  of  expense  in  any  way  connected  with  the  execution  and  maintenance  of  the  work, 
until  it  is  finally  accepted  and  received  as  completed. 

The  Contractor  will  only  be  paid  for  the  piles,  timber,  and  iron  left  in  the  structure  after 
completion.  No  wastage  in  any  kind  of  material  will  be  paid  for  except  in  the  case  of  piles, 
when  the  "  piles'  cut-off,"  and  which  cannot  be  used  on  any  other  part  of  the  Contractor's 
work,  will  be  paid  for  at  the  rate  agreed  upon.  After  the  material  cut  off  is  paid  for  it  is  to 
be  considered  as  the  property  of  the  Railroad  Company,  and  is  neither  to  be  removed  nor 
used  by  the  Contractor  without  the  consent  of  the  Engineer,  and  then  only  upon  the  repay- 
ment of  the  price  which  has  been  paid  for  it. 

The  piles  and  "  piles'  cut-off  "  will  be  paid  for  by  the  lineal  foot,  the  former  to  be  driven 
and  in  place. 

The  timber  and  lumber  will  be  paid  for  by  the  thousand  feet,  board-measure,  remaining 
in  and  necessary  to  the  completed  structure. 

The  iron  will  be  paid  for  by  the  pound  actually  remaining  in  the  structure  after  its  com- 
pletion. 

The  masonry  for  foundations  will  be  paid  for  by  the  cubic  yard. 

The  excavations  for  foundations  will  be  paid  for  by  the  cubic  yard. 

The  retained  percentage  will  not  be  paid  on  the  cost  of  any  single  structure  until  the  final 
estimate  is  due  on  the  entire  work  embraced  in  the  contract. 

If  the  building  of  the  trestle  is  let  with  the  contracts  for  grading  or  under  a  general  con- 
tract, then  many  of  these  clauses  may  be  omitted,  as  they  are  merely  general  requirements 
applicable  to  all  classes  of  work.  Many  of  the  clauses  would  also  be  omitted  or  changed  some- 
what under  the  different  conditions  existing  in  different  sections  of  the  country.  The  effort 
has  been  made,  however,  to  make  them  as  generally  applicable  and  as  concise  as  possible,  and 
all  of  the  clauses  inserted  have  been  selected  on  account  of  their  general  excellence  and  justice 
to  both  Contractor  and  Railroad  Company. 

A  form  of  proposal  is  as  follows  : 

THE  RED  RIVER  RAILROAD  COMPANY. 


PROPOSAL  FOR  BUILDING  TRESTLES. 


The  undersigned  hereby  certify  that  they  have  personally  and  care/idly  ex- 
amined the  location  and  the  plans  and  specifications  for  the  trestles  on  the  first, 
second,  and  third  divisions  on  the  line  of  the  Red  River  Railroad. 

Having  made  such  examinations,  the  undersigned  hereby  propose  to  the  said  Red 
River  Railroad  Company  to  furnish  all  the  material  and  do  all  the  work  required 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES. 


69 


for  the  construction  and  completion  of  said  first,  second,  and  third  division  trestles, 
in  accordance  with  said  specifications  and  plans,  and  upon  the  acceptance  of  this  pro- 
posal do  hereby  bind  themselves  to  enter  into  and  execute  a  contract  for  the  same  at 
the  following 

PRICES: 


Material.    . 

Unit. 

Approximate 
quantities.    May 
be  more  or  less. 

R 

ite. 

Foundation  excavation  —  Earth,      .     .     .     . 

Cubic  yard. 

2? 

22 

Solid  rock,  .     .     . 
Foundation  masonry,     

Cubic  yard. 
Cubic  yard. 

15 
56 

5 

90 
CO 

Round  white-pine  piles,  not  creosoted,  .     . 
«         .<         .<         .<           «     cut  off( 

"                   oak      "        "          " 

Lineal  foot. 
Lineal  foot. 
Lineal  foot. 

1500 

35 
06 

Etc.                etc.               etc. 
Square  yellow-pine  piles,  not  creosoted,  .     . 

Lineal  foot. 
Lineal  foot. 

IOOO 

35 

Etc.               etc.                etc. 
White-pine  timber,  not  creosoted,  erected,  . 
Oak 
Etc.                etc.                etc. 
Round  oak  piles,  creosoted,  

Lineal  foot. 

M.  B.  M. 
M.  B.  M. 

Lineal  foot. 

loo  M. 
10  M. 

172? 

3° 
40 

08 

00 

oo 

7C 

"        "            "      cut  off  
Etc.               etc.                etc. 
White-pine  timber,  creosoted,  erected,   .     . 
Etc.                etc.                etc. 
Wrouerht-iron, 

Lineal  foot. 
M.  B.  M. 
Pound. 

750  M. 
10,000 

3° 

30 
00 

04 

Cast-iron,  

Pound. 

1  2  so 

O2i 

The  undersigned  further  propose  to  commence  work  within  ten  days  from  date 
of  contract,  and  to  complete  the  same  within  sixty  days  from  date  of  contract. 

Signed  this  sixth  day  #/"  January,  1890. 

Name  of  Firm,  SMITH  BROS.  &  COMPANY. 

f  GEO.  H.  SMITH. 
By  \  WM.  R.  SMITH. 
I  ED.  C.  BROWN. 

Post  Office  address  of  Contractor  : 

97  Great  George  Street, 

New  York  City, 

New  York. 

This  form  in  blank,  for  filling  out,  should  be  printed  and  bound  with  the  specifications, 
together  with  the  agreement  or  contract.  Those  portions  of  the  form  printed  in  Roman  type 
are  left  blank  for  filling  in  by  the  bidders,  excepting  in  the  table  of  prices,  where  only  the 
prices  are  left  blank. 


CHAPTER  XI. 
BILLS  OF  MATERIAL,  RECORDS,  AND   MAINTENANCE. 

ONE  of  the  most  perplexing  duties  to  the  young  engineer  is,  perhaps,  the  making  out  of 
proper  bills  of  materials  for  trestle-work.  The  following  is  an  example  of  a  properly  made 
out  bill  of  material : 

TRESTLE  No.  6. 

DIVISION  No.  2;     RESIDENCY  No.  4. 

BILL  OF  TIMBER. 


No.  of 

Number 

Size 

Feet 

Total 

Bent. 

of  Pieces. 

B.  M. 

feet  B.  M. 

I—  H 

eight,  9  f 

eet. 

2 

Cap. 

6"  x  1  2"  xi  4'  o" 

1  68 

2 

Plumb-posts. 

I2"XI2"X     8'0" 

192 

2 

Batter-posts. 

I2"XI2"X     9'0 

216 

I 

Sill. 

12"  x  12"  x  1  2'  4" 

148 

8 

Blocks  —  Mud-sills. 

I2"XI2"X     2'  6" 

240 

964 

2—  H 

eight,  13 

feet. 

2 

Cap. 

6"  x  1  2"  xi  4'  o" 

1  68 

2 

Plumb-posts. 

1  2"  X  1  2"  X  1  21  O" 

288 

2 

Batter-posts. 

12"  x  12"  x  1  3'  2" 

316 

I 

Sill. 

12"  x  12"  x  14'  2" 

170 

2 

Sway-braces. 

3"x  io"x  i6'6" 

83 

8 

Blocks  —  Mud-sills. 

I2"XI2"X     2'  6" 

240 

1265 

3-H 

eight,  10 

feet. 

2 

Cap. 

6"xi2"xi4'o" 

1  68 

2 

Plumb-posts. 

I2"X  I2"X     9'0" 

216 

2 

Batter-posts. 

12"  X  I2"x  IO'  l" 

242 

I 

Sill. 

I2"XI2"X  12'  8" 

152 

2 

Sway-braces. 

3"xio"xi4'o" 

70 

8 

Blocks  —  Mud-sills. 

1  2"  XI  2"^     2'  6" 

240 

1088 

F 

loor  Sys 

tern  and  Miscellaneous  Parts  : 

8 

Bank-sills. 

I2"X  12"  X  12'  0" 

1152 

10 

Stringers  and  Jack-stringers. 

8"xi6"x25'o" 

2667 

4 

Stringers. 

8"x  1  6"  xi  2'  6" 

534 

51 

Ties. 

6vx    8"xi2'o" 

2448 

9 

Guard-rails. 

6"x    8"x2o'o" 

720 

7521 

Grand  Total,  .     .     

10,838 

J 

BILL  OF   IRON. 


No.  of 
Pieces. 

Name. 

Use. 

Size. 

Weight. 

- 

Wrought  Iron. 

24 

Drift-bolts. 

Stringers  to  Bank-sills. 

f  "  sq.  x  24" 

26 

Drift-bolts. 

Stringers  to  Caps. 

f"  sq.  x  24" 

6 

Drift-bolts. 

Sills  to  Mud-sills. 

f  "  sq.  x  20" 

1  02 

Boat-spikes. 

Ties  to  Stringers. 

y  x  12" 

150 

Boat-spikes. 

Guard-rails  to  Ties. 

V'XI2" 

26 

Bolts. 

Guard-rails  to  Jack-stringers. 

£"x3i£" 

12 

Bolts. 

Qips  to  Posts. 

f  "  x  22" 

16 

Bolts. 

Sway-bracing. 

J"  X  20" 

32 

Bolts. 

Packing  for  Stringers. 

i"  X  22" 

Tot 

al, 

Cast  Iron. 

172 

Washers. 

Under  heads  and  nuts  of  Bolts. 

I"X3" 

32 

Separators. 

Between  Stringers. 

2"  X  3" 

Tot 

al, 

Signed, 


Jan.  25,  1890. 


WILLIAM  Boss,  Resident  Engineer. 

70 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  71 

A  copy  of  all  such  bills  as  these  should  be  made  in  a  letter-book.  In  making  out  the 
estimates  of  timber  in  feet,  B.  M.,  the  contractor  should  always  be  allowed  the  full  size  of 
any  stick  between  the  extreme  ends  of  the  tenons,  and  where  the  ends  or  tenons  are  required 
to  be  cut  on  a  skew,  the  full  size  for  the  length  with  square  ends  required  to  cut  the  piece. 

The  following  is  the  rule  for  finding  the  number  of  feet,  B.  M.,  in  any  stick  of  timber,  or 
in  lumber  one  inch  or  over  in  thickness  : 

Multiply  the  breadth  and  thickness  in  inches  together,  and  divide  by  twelve.  Multiply 
this  result  by  the  length  in  feet  and  fractions  of  a  foot,  and  the  final  result  will  be  the  number 
of  feet,  B.  M.,  in  the  stick. 

Putting  this  in  the  form  of  an  algebraic  expression,  we  have 


Feet 


b  =  breadth  in  inches  ; 

/  =  thickness  in  inches  (when  one  inch  or  over)  ; 
L  =  length  in  feet  and  fraction  of  a  foot. 

When  the  lumber  is  less  than  one  inch  in  thickness  it  is  always  counted  as  though  it  were 
a  full  inch  thick. 

It  will  be  found  that  if  such  a  table  as  that  shown  below  be  made  out  for  bents  up  to  a 
moderate  height,  varying  by  six  inches,  and  blue  prints  of  it  sent  to  the  different  resident  and 
division  engineers,  considerable  labor  and  time  will  be  saved,  and  many  annoying,  and  at  times 
serious,  errors  avoided. 


NORTH  AMERICAN  RAILROAD  COMPANY. 
BILL  OF  TIMBER   FOR   STANDARD   TRESTLES. 


PILE. 

PILE. 

Height 
from  surface 
of  Ground  to 
top  of  Cap. 

Caps 
6"  x  12" 

Sway-braces 
3"  x  10" 

Intermediate 
Caps 
3"  x  10" 

Feet 
B.  M. 

Height 
from  surface 
of  Ground  to 
top  of  Cap. 

Caps 

6"    X    12 

Sway-braces 
3"  x  10" 

Intermediate 
Caps. 
3"  x   to" 

Feet 
B.  M. 

Length 

Length 

Length 

Length 

Length 

Length 

Ft.             Ins. 

PCS. 

Ft.  Ins. 

Ft.  Ins. 

Ft.  Ins. 

Ft.             Ins. 

Ft.  Ins. 

Ft.  Ins. 

Ft.  Ins. 

5           o 

2 

14    o 

1  68 

8              0 

5           6 

2 

14    o 

1  68 

8              6 

6            o 

2 

14    o 

9          o 

6            6 

2 

14    o 

9          6 

7            o 

IO              O 

2 

14   o 

2 

16    6 

251 

7            6 

10          6 

II              O 

A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 

FRAMED. 


Height 

Caps 

Plumb-posts 

Batter-posts 

Sill 

Sway-  braces 

Intermediate 
Caps 

Mud-sills 

of  Sill  to 
top  of  Cap. 

3"  x    10" 

Feet 
B  M 

Length. 

Length. 

Length. 

Length. 

Length. 

Length. 

Length. 

Ft.             Ins. 

Ft.      Ins. 

Ft.      Ins. 

Ft.      Ins. 

Ft.      Ins. 

Ft.      Ins. 

Ft.      Ins. 

Ft.      Ins. 

5           o 

2 

14      o 

2 

4      6 

2 

4      6 

I 

16      o 

8 

2         6 

816 

5           6 

6           o 

6            6 

7            o 

7            6 

8           o 

8            6 

9           o 

9           6 

10           o 

10           6 

II                0 

General. — Each  trestle  will  require  : 

8  Bank-sills  12  in.  X  12  in.  X  12  ft 1152  ft.  B.  M. 

4  Dump-boards  4  in.  X  8  in.  X  1 1  ft.  4  in 121"    "    " 

Stringer-pieces  8  in.  X  16  in.  X  25  ft.,  contain  each.  267  "    "    " 

Ties  6  in.  X  8  in.  X  12  ft.                        "          "     ...  48"    "    " 

Guard-rails  6  in.  X  8  in.  X  20  ft.            "          "...  80"    "    " 

Many  other  devices  for  furnishing  aid  in  making  out  bills  of  material  have  been  in- 
vented, and  are  used  to  a  greater  or  lesser  extent  in  the  various  offices  throughout  the 
country.  One  of  the  most  notable  of  those  which  have  come  to  the  Author's  notice,  and 
of  which  the  originator  is  not  known,  is  that  of  drawing  a  bent  to  a  large  scale, — say 
three-quarters  of  an  inch  to  the  foot,  on  paper  that  will  not  vary  much  with  changes  in 
the  atmosphere.  The  sills  for  heights  varying  by  regular  amounts — six  inches  is  very  good — 
are  then  drawn  in.  When  the  length  of  any  part,  for  any  height  of  bent,  is  needed,  it 
can  readily  be  scaled  directly  from  the  drawing. 

Construction  records  in  detail  are,  of  course,  made  out  each  month  for  all  of  the 
trestle-work  built  since  the  previous  estimate  was  taken  up.  The  thoroughness  and  com- 
pleteness of  these  records  vary  considerably  on  different  roads. 

Following  are  some  forms  of  construction  records  as  kept  on  the  Norfolk  &  Western 
Railroad.  These  records  are  very  complete,  and  are  to  be  recommended. 


A    TREATISE   ON    WOODEN    TRESTLE   BRIDGES. 


73 


MASONRY  EXHIBIT  OF  TRESTLE-FOOTINGS. 

Show  cross-sec- 
tion of  irregular 
and  stepped  foot- 
ings, also  skew- 
bents. 

CJ   J3 

Zfj 

3  a 

93UBJS1Q 

LENGTH  OF  FOOTING. 

a 

tf 

tt 
c 

u 

d 

U 

V 

J 

ELEVATIONS. 

BOTTOM  OF  MASONRY. 

Distance 
from  centre. 

i 

Centre. 

V 

H-l 

Distance 
from  centre. 

Top  OF  MASONRY. 

1 

Centre. 

•I 

GROUND. 

1, 

Pi 

Centre. 

i 

o      x 

*J«4-I     U 

JS  U  0  C 
1/5  g  2  rt 

<^  fc. 

l"o| 

o 
p 

to 

This  sheet  is  13^  in.  long  by  8|  in. 
wide,  and  is  ruled  horizontally  in  blue 
ink,  with  five  lines  to  the  inch. 

It  is  indorsed  on  the  back  for  filing 
as  follows : 


NORFOLK  &  WESTERN  RAIL- 
ROAD. 

CONSTRUCTION   DEPARTMENT. 


MASONRY  EXHIBIT  OF  TRESTLE-FOOTINGS, 

Trestle  No 

Section  No 

Estimate  No 

18.. 

Contractor. 

. .  Cubic  Yards. 


This  indorsement  is  so  placed  that 
it  will  be  on  the  outside  when  the  sheet 
is  folded  into  four  parts  across  its  length 
so  as  to  make  a  bundle  about  3$  in.  by 
Win. 


74 


./     TREATISE   OM    WOODEN    TRESTLE   BRIDGES. 
NORFOLK   &   WESTERN    RAILROAD   CO. 


Timber  Estimate  No 18. 

Trestle  No Section  No Res Contractors. 

East  End  of  Stringers,  Sta West  End,  Sta Length feet. 


STATION. 

|| 

SHOULDER  TO  SHOULDER. 

OVER  ALL. 

Plumb  Post. 

Outside 
Batter  Post. 

Inside 
Batter  Post. 

Sill. 

Diagonal 
Bracing. 

Longitudinal 
Bracing. 

No. 

Length. 

'No. 

Length. 

No. 

Length. 

No. 

Length. 

No. 

Length. 

No.'   Length. 

Add  Tenons, 

Totals, 

SUMMARY. 

fl 

isions. 

in 

U 

N 

(75 

u 
E 

5 

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5c 

5 

tn 

U 

u 

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CU 

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£                                                                                  be 

«  «                      ^  "                 -  1  cl  '3  -   "                      «" 

CuOhS             toU-S             u        ^c/i        Q        J        £        r£c£d!        HOS 

o 

A    TREATISE  OF    WOODEN   TRESTLE  BRIDGES. 


75 


This  sheet  is  of  the  same  size  and  indorsed  upon  the  back  in  the  same  manner  as  the 
foregoing  one.     The  indorsement  is  as  follows : 


0 

< 
o 

ttJ 
hJ 


OS 

w 

C/3 

w 


4 


os 
O 


UJ 
UJ 

I 

CO 


UJ 

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UJ 


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DC 

f- 


00 


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'§ 


Now,  if  no  more  than  one  trestle  is  put  upon  any  one  sheet,  the  sheets  may  be  bound  in 
their  proper  order  upon  the  completion  of  the  road,  and  will  then  form  excellent  records  for  the 
use  of  the  Maintenance  of  Way  Department.  These  blanks  are,  of  course,  filled  out  and  signed 
by  the  Resident  Engineer,  and  their  summaries  entered  upon  the  "  Detail  Item  Sheet"  of  the 
Residency  for  the  corresponding  month.  These  should  then  be  forwarded  to  the  Division 
Engineer,  who  compiles  the  following  report  from  those  of  the  several  Residencies  under  him: 

NORFOLK  &  WESTERN  RAILROAD  COMPANY. 
Estimate  No 


18 


Division. 

BRIDGE,   TRESTLE   AND   TIMBER   ESTIMATE. 


Contractor. 


DESIGNATION 

OF 

^    STRUCTURE. 
in 

CHARACTER 

OF 

STRUCTURE. 

IRON  BRIDGES. 

WOODEN  BRIDGES. 

TIMBER 
DELIVERED. 

TIMBER 
FRAMED. 

TRESTLE 
ERECTED. 

IRON, 
BOLTS, 

ETC. 

REMARKS. 

Length 
Out  to  Out. 

Length 
Out  to  Out. 

Pine. 

Oak. 

TOTAL  TO  DATE 
PREVIOUS  ESTIMATE  NO. 
CURRENT  ESTIMATE. 


76 


A    TREATISE   OF    WOODEN    TRESTLE   BRIDGES, 


This  sheet  is  7  in.  by  17  in.,  and  is  intended  to  be  folded  once  each  way.     One  half  of  the 
back  is  ruled  for  a  summary  as  follows  : 


SUMMARY. 


ITEMS. 

PKKVIOTS 
RSTI.MATK. 

ClIRKENT 

KSTIMATK. 

TOTAL 
TO  DATK. 

RATE. 

AMOUNT. 

Certified  b\  

TOTAL  AMOUNT. 

On  one  half  of  the  remaining  half   of   the   back  is  the  following  indorsement  for  filing 
purposes  : 


DC 

V 



--  — 

Lu 
CQ 

o: 

ts, 

>     ? 

k 

CJ 

'>J 

^ 

h- 

•K. 
H* 

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O 

O 

After  the  road  has  been  finished  and  turned  over  to  the  operating  and  maintenance 
departments,  inspections  of  the  trestles,  the  same  as  with  all  the  other  properties,  should  be 
frequently  and  regularly  made.  As  to  the  frequency  of  these  special  inspections  the  practice 


A    TREATISE   OF    WOODEN    TRESTLE  BRIDGES. 


77 


and  opinions  vary.  A  personal  inspection  of  all  the  structures  by  the  Engineer  of  Main- 
tenance of  Way  or  of  Bridges  and  Buildings  should  be  made  at  least  once  a  year  at  an 
auspicious  season.  On  the  New  York,  Lake  Erie  &  Western  Railroad  this  inspection  is 
required  twice  a  year.  Of  course  inspections  of  single  structures  should  be  made  at  any 
time  when  the  necessities  of  the  case  demand  them.  It  is  good  practice,  where  there  is 
any  considerable  amount  of  trestling  and  bridging  on  a  division,  to  have  a  competent  inspector 
whose  sole  business  is  to  inspect  and  oversee  repairs  to  the  structures.  He  should  personally 
and  carefully  examine  every  structure  under  his  charge  once  every  month,  or  two  months,  as 
the  location  of  the  road  may  require,  and  report  their  condition  on  proper  blanks  to  the 
Division  Engineer  cr  Division  Superintendent.  These  officers,  in  their  turn,  after  examining 
and  approving  these  reports,  should  forward  them  to  the  Engineer  of  Maintenance  of  Way, 
or  the  Engineer  of  Bridges  and  Buildings,  as  the  case  may  be.  Every  part  of  each  structure 
should  be  carefully  and  critically  examined  from  all  sides,  and  the  inspector  should  be  required 
under  all  circumstances  to  examine  trestles,  not  only  from  their  deck,  but  also  from  beneath. 
Proper  facilities  should  be  afforded  him  for  this  purpose.  In  urgent  cases  he  should  report  by 
telegraph  or  letter  from  the  nearest  station,  as  the  matter  may  require.  In  addition  to  this 
the  track-walkers  should  keep  a  constant  watch  upon  all  trestles,  and  report  their  condition 
daily  to  the  inspector.  A  pad  ruled  as  follows  will  be  found  very  convenient  for  the  track- 
walkers to  make  these  reports  upon : 

NORTH  AMERICAN  RAILROAD   COMPANY. 

TRACK-WALKER'S  DAILY  REPORT  ON  THE  CONDITION  OF  BRIDGES  AND  TRESTLES. 


NUMBER  OF  BRIDGE. 

TIME. 

CONDITION. 

A.M. 

P.M. 

A.M. 

P.M. 

ISO 

lO^O 

1:40 

X 

X 

IS' 

945 

3:15 

X 

X 

152 

153 

154 

'55 

Track-walker. 
..18. 


Six  inches  wide  by  seven  inches  long,  with  fifty  sheets  in  a  pad,  is  a  very  good  size.  It 
is  also  advisable  to  have  a  cardboard  cover  which  will  shut  over  the  face  of  the  pad  in  the 
same  manner  as  the  cover  of  a  book. 

The  sheets  are  folded  across  for  filing,  with  the  following  indorsement  on  one  half: 

NORTH   AMERICAN  RAILROAD  COMPANY. 

TRACK-WALKER'S  DAILY  REPORT. 
BRIDGES  AND  TRESTLES  Nos.  150  TO  155. 

18.... 

Track-walker. 


78  A    TREATISE   OF    WOODEN    TRESTLE  BRIDGES. 

On  the  other  half  of  the  back  these  instructions  are  printed : 

INSTRUCTIONS  TO  TRACK-WALKERS: 

You  will  carefully  examine  each  bridge  and  trestle  over  which  you  may  pass,  and  enter  their  condition 
in  the  proper  column  and  on  the  proper  line  of  this  blank. 

You  will  also  enter  the  time  of  such  examination  in  the  proper  column  and  on  the  same  line. 

X  in  the  column  headed  "  Condition"  means  "  all  right." 

O  means  injured,  or  unsafe  by  fire,  washout,  or  other  means. 

These  reports  must  be  forwarded  every  evening  to  the  Inspector  of  Bridges. 

A  report  must  be  made  out  every  time  a  bridge  or  trestle  is  passed  over,  even  if  three  or  four  times  a  day. 

In  case  of  O,  such  fact  must  be  telegraphed  atonceivom  nearest  office  to  the  Inspector  of  Bridges,  the 
Division  Engineer,  and  the  Division  Superintendent. 

A  repeated  disregard  of  these  instructions  will  be  considered  a  sufficient  cause  for  discharge. 

An  axe  or  hatchet  and  a  small  auger  are  absolutely  indispensable  to  an  inspector 
for  the  proper  performance  of  his  duty.  Frequently  the  soundness  of  a  piece  of  timber 
can  be  tested  by  pounding  upon  it  with  a  hammer,  and  listening  to  the  sound  which  the 
blows  make.  In  case  of  any  question,  a  hole  should  be  bored  into  the  timber  with  the 
auger.  This  will,  of  course,  settle  the  matter  beyond  all  doubt.  These  holes  should  always 
be  filled  up  immediately  after  boring  them,  either  by  driving  a  plug  in  very  tightly  or  with 
putty  It  is  not  advisable  to  bore  many  holes  in  one  piece  of  timber,  as  they  greatly  weaken 
it.  A  better  way  to  arrive  at  a  just  conclusion,  it  seems,  is  to  drive  in  a  long,  thin  nail,  such 
as  a  wire-nail.  The  degree  of  ease  with  which  the  nail  penetrates  the  wood  is  a  very  good 
test  of  its  condition.  In  pile-trestles  on  land,  where  the  foot  of  the  piles  can  be  reached,  it  is 
very  good  practice  to  dig  away  the  ground  around  them,  for  a  foot  or  so  in  depth,  once  every 
twelve  or  eighteen  months,  in  order  that  the  least  durable  part  may  be  inspected.  After  the 
inspection  the  earth  is  replaced  and  properly  tamped.  This  inspection  need  not  be  begun 
until  after  the  pile  has  been  in  the  ground  for  several  years.  The  length  of  time  which  it  is 
advisable  to  allow  to  elapse  before  beginning  it  will  depend  largely  upon  the  kind  of  timber. 
Thorough  records  of  all  these  inspections  should  be  carefully  made  and  preserved.  In  order 
to  be  able  to  properly  and  definitely  locate  any  part  of  any  structure  beyond  the  question  of 
a  doubt,  all  of  the  bridges,  trestles,  etc.,  should  be  numbered  consecutively,  beginning  at  one 
end  of  road  and  going  toward  the  other.  Then  in  each  trestle  the  bents  should  be  numbered 
in  the  same  direction  ;  the  stringers,  guard-rails  and  longitudinal  bracing  should  also  be  num- 
bered from  right  to  left ;  the  ties  over  each  bay  should  be  numbered  ;  and  finally,  the  stories 
beginning  at  the  top  and  going  to  the  bottom,  should  be  treated  similarly.  By  this  means  any 
one  acquainted  with  the  system  of  the  road  can  take  a  description  of  any  part  from  the  Bridge 
Book,  and  locate  it  upon  the  ground  beyond  all  question. 


A    TREATISE  ON    \VOODEN    TRESTLE  BRIDGES, 


79 


A  heading  suitable  for  the  inspector's  reports  and  records  is  as  follows  : 

NORTH  AMERICAN  RAILROAD  COMPANY. 

MAINTENANCE  OF  WAY  DEPARTMENT. 

Bridges  No.  —  to  No.  —  TRESTLE  INSPECTION. 

S3JJBUI3H 

UOI1DD10JJ 
3JIJ  JO 

uoi»!pu<>3 

•UO4I 

Longitudinal 
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Stringers. 

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So  A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 

Every  space  opposite  a  bent  should  be  filled  in  to  show  that  that  part  has  been  examined. 
If  there  is  no  such  part,  a  line  should  be  drawn  through  the  space.  The  filling  in  of  the 
report  should  be  done  on  the  ground.  After  the  reports  are  sent  to  the  Engineer  of  Main- 
tenance of  Way  they  may  be  placed  in  proper  order  and  bound.  These  reports  should  be 
forwarded  at  regular  and  stated  intervals,  and  a  copy  of  them  kept  by  the  Division  Engineer. 

They  should  be  on  paper  about  24  in.  long  by  12  in.  wide,  padded  in  lots  of  one  hundred 
sheets,  in  a  similar  manner  to  the  Daily  Reports  of  Track-walkers.  Two  or  three  blotting- 
sheets  should  be  attached  to  the  front  cover,  and  the  filling-in  required  to  be  done  in  ink, 
a  fountain  or  stylographic  pen  being  useful  for  this  purpose.  The  instructions  and  affidavit 
may  either  be  printed  at  the  bottom  or  on  the  back  of  the  sheet,  as  is  found  most  desirable. 

The  following  is  the  order  of  inspection  required  upon  the  Plant  system  of  railways  in 
South  Carolina,  Georgia,  and  Florida:* 

Number  of  bents,  piles,  sills,  legs,  caps,  corbels,  chords,  posts,  braces,  stringers,  floor- 
beams,  condition  of  cross-ties.  Do  piles  in  this  bridge  or  trestle  settle?  If  so,  state  condi- 
tion of  shims,  number  of  feet  of  standard  guard-timber,  condition. 

Is  the  opening  subject  to  wash  at  end,  or  at  bottom  ? 

Total  length  of  bridge.     Longitudinal  braces  every  bent,  size,  condition. 

Are  abutments  protected  by  rock,  revetment  timbers,  or  any  other  protection?  Condi- 
tion of  such  protection. 

A  certificate  as  to  the  truth  of  the  inspection  is  then  given  by  the  inspector. 

The  inspector  should  have  direct  charge  of  all  bridge-repair  gangs  working  on  his 
division,  and  all  orders  or  instructions  to  the  men  transmitted  through  him,  and  he  be  held 
responsible  for  their  proper  execution. 

The  following  are  the  instructions  issued  by  the  New  York,  Lake  Erie  &  Western  Rail- 
road, and  the  Burlington,  Cedar  Rapids  &  Northern  Railroad,  in  regard  to  bridge-work : 

BRIDGE  INSPECTION  ON  THE  ERiE.f 

Under  the  system  of  inspection  and  reports  now  in  force  on  the  Erie  there  are  employed  10  inspectors 
who  report  directly  to  their  respective  Division  Roadmasters  each  month,  and  every  three  months  the  Divi- 
sion Roadmasters  make  inspections  and  report  to  the  Division  Superintendents.  These  quarterly  reports 
are  forwarded  through  the  General  Roadmaster  and  General  Superintendent  to  the  Engineer  of  Bridges  and 
Buildings,  in  whose  office  they  are  filed.  The  inspectors  have  no  other  duties  than  those  of  inspection. 

The  blank  forms  for  the  inspectors'  reports  are  on  sheets  20  inches  square.     The  heading  of  the  sheet 
is  as  follows : 
Form  X.  402.  N.  Y.,  L.  E.  &  W.  R.  R.  CO. 

REPORT   SHOWING   CONDITION  OF   BRIDGES   ON   THE DIVISION,  MONTH   ENDING l8...  . 

The  sheet  is  ruled  in  17  vertical  columns,  of  which  the  headings  are  as  follows:  Number;  Kind  of 
Bridge,  Wooden  or  Iron  ;  General  Conditions  of  Masonry,  Bed  Plates,  Rollers  and  Frames,  Pedestals,  Main 
Trusses  or  Girders,  Lateral  System,  Iron  Floor  System,  Rivets,  Hangers,  Castings,  Paint ;  Action  under 
Trains;  Date  of  Inspection;  Remarks  and  Recommendations.  This  is  to  be  signed  by  the  Inspector,  n;:<i 
at  the  foot  is  further  space  for  remarks.  On  the  back  of  the  sheet  are  printed  the  following  orders  and 
directions  : 

NEW  YORK,  LAKE  ERIE  &  WESTERN  R.   R.  CO. 

GENERAL   ORDERS    FOR  THE   INSPECTION   OF   BRIDGES. 

1.  Besides  the  constant  and  careful  examination  of  all  bridges  by  the  regular  Inspector,  each   Road- 
master  shall  make  a  personal  and  thorough  inspection  of  the  same  once  every  three  months. 

2.  A  regular  report  of  the  condition  of  every  bridge  shall   be  made   by  the  Inspector  to  the   Division 
Roadmaster  every  month,  upon  blanks  furnished  for  that  purpose. 

*  Maj.  C.  S.  Gadsden,  Railroad  Gazette,  1888,  p.  652.  \  Railroad  Gazette,  July  29,  1887. 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  8r 

3.  The  quarterly  examination  made  by  the  Roadmaster  shall  be  reported  upon  form  No.  X,  402  A,  but 
must  be  signed  by  him  and  forwarded  to  the  Division  Superintendent,  who  shall  in  turn  transmit  it  through 
the  proper  channels  to  the  Engineer  of  Bridges  and  Buildings. 

4.  The  Engineer  of  Bridges  and  Buildings  will  also  make  a  stated  personal  examination  of  all  bridges 
twice  a  year,  besides  the  customary  inspection  of  special  cases,  as  reported  from  time  to  time,  and  upon  the 
request  of  the  General  Superintendent. 

5.  The  condition  of  the  different  parts  of  the  bridges  must  be  briefly  stated  under  the  appropriate  heads 
on  the  blanks  furnished,  and  in  case  of  need,  further  information  shall  be  given  in  the  column  of  "  Remarks 
and  Recommendations." 

6.  Special  reports  by  letter  or  telegraph,  according  to  the  urgency  of  the  case,  must  be  made  by  the 
Inspector  or  Roadmaster  wherever  any  fault  or  defect  is  discovered  that  may,  in  their  judgment,  endanger 
the  safety  of  the  bridge. 

7.  All  ordinary  repairs,  such  as  tightening  loose  rivets  and  renewing  wooden  floors  on  iron  bridges,  or 
replacing  such  parts  of  wooden  structures  as  have  become  defective  by  age  and  are  necessary  for  the  safety 
of  the  bridge,  shall  be  done  without  special  orders. 

8.  When,  however,  alterations,  additions,  or  expensive  renewals  of  any  bridge  are  contemplated  and 
become  necessary,  they  must  be  reported  to  the  Engineer  of  Bridges  and  Buildings,  who  will  then  prepare 
the  necessary  plans  and  estimates  for  approval.  R.  H.  SOULE,  General  Manager. 


DIRECTIONS,  GIVING  THE   MOST   IMPORTANT   POINTS  TO   BE  OBSERVED   WHILE   INSPECTING   BRIDGES. 

Masonry. 

1.  Each  pier  and  abutment  should  be  carefully  looked  over,  especially  those  that  have  already  given 
signs  of  yielding,  either  by  settling  in  their  foundations  or  by  bulging  from  the  pressure  of  the  embankment 
they  sustain. 

2.  Examine  closely  all  pedestal  stones,  looking  for  cracks  or  evidence  of  crushing;  they  must  be  main- 
tained level  and  firmly  bedded  upon  the  bridge-seats. 

3.  Keep  the  latter  clean  and  free  from  all  rubbish  and  cinder  or  coal,  especially  around  the  iron  bed-plates. 

Iron  Bridges. 

5.  Examine  carefully  all  pedestals,  bed-plates,  and  rollers  and  their  frames.     The  bed-plates  should  be 
perfectly  level,  the  rollers  should  move  freely  and  their  axes  should  always  be  kept  at  a  right  angle  to  the 
line  of  the  bridge.     The  pedestals  should  be  free  from  all  cracks  and  flaws,  and  have  a  uniform  bearing  upon 
all  the  rollers  or  upon  the  bed-plate  at  the  fixed  end. 

8.  In  the  main  trusses  look  most  closely  at  all  the  tension  members,  the  rods  and  bottom  chords, 
especially  where  they  are  composed  of  more  than  one  member.  If  perfect,  they  should  all  be  equally  strained 
per  square  inch  in  any  one  panel,  and  when  they  are  not,  when  one  member  is  slack  and  the  other  tight,  the 
case  should  be  reported  at  once.  The  compression  members,  that  is,  the  posts  and  top  chords,  should  be 
straight,  without  a  bend  or  bulge,  and  all  the  joints  should  bear  closely  against  each  other.  The  counter 
rods  ought  never  to  be  allowed  to  hang  loose,  but  they  must  not  be  adjusted  while  a  load  is  upon  the  bridge, 
and  they  must  not  be  tightened  more  than  just  enough  to  get  a  good  bearing. 

6.  All  hangers,  by  which  floor-beams  or  stringers  are  suspended,  must  constantly  receive  the  closest  attention. 
Their  bearing  around  the  pins  should  always  be  equal  and  uniform  over  half  the  circumference  of  the  lat- 
ter.    If  the  hangers  are  made  of  round  or  square  iron  they  must  be  examined  with  great  care  in  the  semi- 
circle where  they  are  bent  around  the  pins,  and  where  flaws  or  fracture  are  most  likely  to  occur,  and  it  is  of 
the  utmost  importance  that  the  nuts  on  the  ends  of  such  hangers  supporting  the  whole  floor  of  the  bridge 
are  never  permitted  to  become  loose.     A  white  streak  painted  across  the  face  of  the  nut  and  its  bearing 
will  make  it  easy  to  detect  at  once  any  motion  in  the  nut. 

7.  The  places  where  stringers  are  riveted  or  otherwise  fastened  to  the  floor-beams,  and  which  are  generally 
not  easy  of  access  for  inspection,  on  account  of  the  wooden   floor  over  them,  must  be  frequently  and  thor- 
oughly examined.     Here  the  rivets  are  most  likely  to  get  loose,  and  the  webs  and  flanges  of  the  beams  and 
stringers  are  more  liable  to  fail  from  shearing  or  crushing  than  anywhere  else. 

8.  The  lateral  systems  and  sway-bracing  must  never  be  neglected  when  a  bridge  is  inspected.     All  the 
rods  should  be  tight  but  not  overstrained,  as  the  struts  are  liable  to  be  crippled  if  too  much   power  is  used 
in  adjusting  the  tension  members. 

9.  Cast-iron  parts  of  all  bridges,  more  particularly  when  in  top  chords  or  in  joint  boxes,  must  be  closely 
examined.     Should  any  cracks  or  breaks  be  discovered  the  fact  must  be  at  once  reported.     A  hole,  of  J  in. 
diameter  if  drilled  at  the  end  of  a  crack  will  frequently  stop  its  extending  further. 


82  A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 

10.  Riveted  work  should  frequently  be  sounded  with  a  hammer  to  detect  loose  rivets;  and  if  they  can- 
not be  tightened  at  once  their  number  and  location  must  be  reported  on  the  monthly  report. 

11.  No  water  must  be  allowed  to  collect  in  the  interior  of  any  cast  or  wrought  iron  parts  ;  drain-holes 
should  be  kept  open  for  that  purpose,  and  must  be  provided  if  they  do  not  exist. 

Wooden   Bridges. 

12.  After  a  wooden  bridge  or  trestle  has  been  in  use  over  three  years,  a  close  inspection  must  be  made 
twice  a  year  as  to  the  condition  of  the  timber,  by  boring  holes  in  suspicious-looking  places,  especially  near 
the  bridge-seats  and  at  the  ends  of  stringers  and  braces.     The  nature  of  the  boring  will  reveal  the  fact  if  the 
timber  is  sound  or  decaying.     Whenever  splices  exist  in  bottom  chords,  and  principally  in  long-span  bridges 
where  they  generally  occur  in  every  panel,  it  is  very  important  to  examine  them  thoroughly  and  to  note  if 
they  are   pulling  apart,  which  would   indicate  a  weakness  or  a  defective  clamp.     The  braces  and  counter- 
braces  should  always  have  a  square  and  even  bearing  upon  the  angle-blocks,  and  the  sliding  away  from  their 
true  position,  if  any,  would  be  sure  evidence  that  the  bridge  needs  immediate  adjustment. 

13.  Tubs  filled  with  water  and  buckets  should  be  kept  constantly  on  hand  on  every  span  of  all  wooden 
bridges. 

General  Conditions. 

14.  The  action  of  a  bridge  under  a  passing  tivin  is  the  best  practical  test  of  its  stability,  and  no  inspec- 
tion shall  be  completed  without  having  made  such  observation,  and  without  having  carefully  noted  any 
undue  deflection,  swaying  or  twisting  of  the  bridge  as  a  whole  or  any  part  thereof. 

15.  The  Roadmaster  should  carefully  measure  with  an  instrument  the  absolute  deflection  and  swaying 
of  any  bridge  reported  to  him  by  the  Inspector  as  doubtful,  and  if  the  movements  are  excessive  must  report 
the  fact  at  once. 

16.  The  tracks  on  the  bridges  as  well  as  on  the  approaches  thereto  should  always  be  in  good  line  and 
surface ;  they  should  be  firmly  bedded  on  the  approaches,  so  as  to  avoid  any  undue  shock  when  a  train 
comes  on  a  bridge  at  a  high  rate  of  speed.  C.  W.  BUCHHOLZ, 

Engineer  of  Bridges  and  Buildings. 

This  form  is  folded,  and  on  the  outer  fold  is  the  indorsement  for  filing  under  the  proper  division  and 
date. 

The  form  for  the  report  of  the  quarterly  inspection  of  the  Roadmaster  is  precisely  the  same,  except  that 
the  sheet  is  20  in.  x  25  in.,  to  give  room  for  three  columns  of  remarks.  These  columns  bear  the  headings, 
By  Roadmaster.  By  Div.  Superintendent,  and  by  Gen'l  Roadmaster,  and  are  signed  by  these  officers  respec- 
tively, and  the  whole  is  signed  by  the  General  Superintendent  when  examined,  approved,  and  forwarded  by 
him  to  the  Engineer  of  Bridges  and  Buildings. 

INSTRUCTIONS  TO   BRIDGEMEN  ON  THE   BURLINGTON,  CEDAR   RAPIDS  AND  NORTHERN 

R.  R.;  H.  F.  WHITE,  CHIEF  ENGINEER^ 

INSTRUCTIONS    TO    BRIDGEMEN. 

1.  You  will  be  furnished  with  the  bill  of  material  needed  for  each  structure  before  your  men  are  sent  out 
on  the  work.     You  must,  as  soon  as  you  reach  the  bridge  site,  check  the  material  delivered  with  your  bill  to 
see  that  both  agree,  and  must  personally  ascertain,  as  quickly  as  possible,  if  the  bill  of  material  includes  all 
that  will  be  required.     If  the  requisite  amount  of  material   is  not  delivered,  you,  must  notify  the  Master 
Builder  of  the  deficiency,  that  the  same  may  be  forwarded  promptly.     Any  material  unfit  or  not  proper  for 
the  structures  will  be  reported  without  delay,  that  another  kind  may  be  substituted. 

2.  You  must  see  before  starting  for  work  that  you  are  fully  equipped  with  the  necessary  tools  to  do  your 
work.     You  must  bear  in  mind  that  you  are  liable  to  be  called  away  at  any  time  from  work  upon  which  you 
may  be  employed,  to  that  of  a  more  pressing  nature,  and  in  order  that  you  may  be  fully  prepared   for  such 
exigencies  must  see  that  you  have  the  facilities  at  hand  for  moving  from  place  to  place,  at  short  notice,  and 
are  provided,  as  far  as  practicable,  with  the  necessary  tools  to  do  all  kinds  of  bridge  work. 

3.  All  bridgemen  are  expected  to  be  prompt  at  the  depot  when  it  is  necessary  for  them  to  take  trains  to 
reach  their  work  ;  as   far  as  possible,  they  will   be  expected  to  board  near  the   place  where  they  work. 
Repeated  failures  to  be  in  time  for  trains  will  be  considered  good  grounds  for  dismissal ;  men  so  left  will  be 
docked  for  time  in  transit  when  they  take  the  next  train,  and  receive  pay  only  for  time  actually  at  work. 

4.  All  men  in  the  service  of  the  company  must  report  to  the  head  of  their  department  any  misconduct 
or  negligence  affecting  the  interests  or  safety  of  the  road  or  property,  and  which  may  come  within  their 
knowledge.     The  withholding  of  such  information  to  the  detriment  of  the  company's  interests  will  be  con- 
sidered a  proof  of  negligence  and  indifference  to  the  company's  interests. 

\KailroadGazette,  Sept.  21,  1883. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  83 

5.  Foremen  must  actively  engage  in  their  work  with  their  men,  and  see  that  all  the  force  working  under 
their  orders  faithfully  perform  their  duties  and  work  full  time. 

6.  Bridgemen  will  be  held  responsible  for  all  company  tools  and  material  put  in  their  charge.     In  case 
of  breakage  or  loss,  the  company  reserves  the  right  to  withhold  from  money  now  or  hereafter  due  them,  a 
sufficient  amount  to  repair  or  replace  them,  as  may  be  thought  best  by  the  head  of  department. 

7.  You  must  fill  out  in  full  all  blanks  and  forward  the  same  in  accordance  with  instruction  given,  and 
must  inform  yourself  about  all  rules  and  regulations  of  the  company,  and  be  governed  accordingly  in  the 
prosecution  of  your  work,  and  must  study  and  always  have  a  copy  of  the  time-card  in  force. 

Hand-cars  must  not  be  left  on  the  track  when  not  in  use,  but  must  always  be  safely  cared  for. 
Signals  must  always  be  put  out  at  the  proper  distance  when  the  roadway  is  not  in  good  condition  for  the 
passage  of  trains. 

8.  You  must  see  that  your  men  are  not  unnecessarily  exposed  to  accidents  which  will  ;n  any  way  render 
the  company  liable  for  damages. 

9.  Bridgemen  are  expected  to  pay  their  own  board  promptly,  and  in  case  of  failure,  the  company  reserves 
the  right  to  withhold  from  money  now  or  hereafter  due  them  a  sufficient  amount  to  pay  the  same,  but  does 
not  assume  any  responsibility  for  board.     A  repetition  of  the  offence  will  be  considered  sufficient  cause  for 
dismissal. 

10.  Tools  must  not  be  carried  into  the  ladies'  car,  and  employes  of  the  bridge  department  must  not 
occupy  seats  when  by  so  doing  passengers  are  obliged  to  stand. 

11.  Any  employes  not  disposed  to  comply  with  these  instructions  are  requested  to  leave  the  employ  of 
the  company  at  once.     The  orders  will  be  read  to  or  by  each  man  employed  before  he  commences  work. 
Any  failure  to  have  this  done  will  subject  the  Foreman  to  discharge  from  service. 

12.  Bridgemen,  in  cases  of  necessity,  will  be  expected  to  work  on  Sunday,  at  the  same  rate  as  paid  for 
work  done  on  the  other  days  of  the  week. 

It  is  the  practice  on  some  roads  to  give  premiums  to  the  bridge-foreman  who  puts  in  his 
timber  at  the  least  cost  per  thousand  feet,  board  measure.  On  the  Charleston  &  Savannah 
Railroad*  the  practice  is  as  follows : 

"  General  Order  188,  paragraph  9,  provides  for  a  premium  for  bridge-foremen. 

"  At  the  end  of  each  three  months  the  bridge-foreman  who  shall  have  put  his  timber  in 
at  the  least  cost  per  thousand  feet,  B.  M.,  will  be  rewarded  with  a  premium  of  fifteen  ($15) 
dollars.  At  the  same  time  a  premium  of  ten  ($10)  dollars  will  be  given  to  the  bridge-fore- 
man who  shall  have  made  the  next  best  showing. 

"  The  conditions  of  these  premiums  are  as  follows  : 

"  (A)  Only  the  actual  time  devoted  to  bridge- work  will  be  considered,  and  fifteen  (15) 
minutes  will  be  allowed  for  each  train  passing  during  working  hours. 

"  (B)  All  timber  put  in  will  be  considered. 

"  (c)  The  work  done  must  be  strictly  workmanlike,  and  in  accordance  with  the  standard 
plans." 

As  to  the  wisdom  of  adopting  this  premium  system  on  all  roads,  it  would  be  difficult  to 
determine.  Whether,  in  many  instances,  it  might  not  lead  to  the  slighting  of  work,  where  it 
would  be  difficult  or  impossible  to  discover  it,  is  a  very  serious  question. 

The  tools  required  in  repair-work  are  much  the  same  as  those  for  building  purposes.  In 
addition  to  those  described,  a  claw-bar,  for  drawing  spikes,  drift-bolts,  etc.,  will  be  necessary. 
A  small  hydraulic  jack  will  frequently  be  found  very  serviceable. 

For  the  purpose  of  designating  the  bridges  and  other  similar  structures,  as  spoken  of  in 
the  first  part  of  this  chapter,  bridge-numbers,  as  they  are  called,  are  used.  These  are  gen- 
erally made  of  pieces  of  2-in.  plank  attached  to  the  bridge  near  one  end  by  |-in.  by  4~in.  lag- 
screws  with  wrought-iron  washers.  Two  forms  of  bridge-numbers  are  illustrated  in  Figs.  149 
and  150. 

*  Maj.  C.  S.  Gadsden,  Supt.  Clias.  &  Sav.  R.R.,  on  "Care  of  Trestles;"  Railroad  Gazette,  1888,  p.  652. 


84 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


The  boards   should  be    planed   and   painted  white  with  several  coats  of  white-lead,  or, 
better   still,  zinc-white,  ground  in  good  linseed-oil.     The  figures  (Fig.  150)  are  black,  three 


109 


FIGS.  149,  150. — BRIDGE-NUMBERS. 

inches  in  height,  with  the  base  fourteen  inches  below  the  top  of  the  board.  The  numbers 
should  be  placed  on  the  bridges  with  uniformity,  i.e.,  they  should  occupy  the  same  relative 
position  on  all  the  structures.  For  example,  the  following  is  the  rule  for  placing  them  on  the 
Atlantic  &  Pacific  Railroad  : 

Position. — East  side  of  right-hand  end  of  cap  on  bent,  fifteen  feet  from  last  or  initial  end 
of  bridge. 

Mr.  D.  J.  Whittemore,  Chief  Engineer  of  the  Chicago,  Milwaukee  &  St.  Paul  systems, 
says  that  on  his  roads*  "everything  not  covered  with  earth,  except  cattle-guards,  be  the 
span  ten  or  four  hundred  feet,  is  called  a  bridge.  Everything  covered  with  earth  is  called  a 
culvert.  Wherever  we  are  far  removed  from  suitable  quarries,  we  build  a  wooden  culvert  in 
preference  to  a  pile-bridge,  if  we  can  get  six  inches  of  filling  over  it.  These  culverts  are  built 
of  roughly-squared  logs,  and  are  large  enough  to  draw  an  iron  pipe  through  them  of  sufficient 
diameter  to  take  the  water.  We  do  this  because  we  believe  that  we  lessen  the  liability  to 
accident,  and  that  the  culvert  can  be  maintained,  after  decay  has  begun,  much  longer  than  a 
piled  bridge  with  stringers  to  carry  the  track.  Had  we  good  quarries  along  our  line,  stone 
would  be  cheaper  [in  maintenance  and  final  cost,  but  not  in  first  cost. — F.].  Many  thousands 
of  dollars  have  been  spent  by  this  company  in  building  masonry  that,  after  twenty  to  twenty- 
five  years,  shows  such  signs  of  disintegration  that  we  confine  masonry  work  now  only  to  stone 
that  we  can  procure  from  certain  quarries  known  to  be  good." 

Mr.  Whittemore  is  an  engineer  of  great  experience,  skill,  and  judgment,  and  there  is 
food  for  much  reflection  in  these  words  of  his.  First,  that  it  is  better  to  use  temporary 
wooden  structures,  to  be  afterward  renewed  in  good  stone,  rather  than  to  build  of  the  stone 
of  the  locality,  unless  first-class.  Second,  that  a  structure  covered  with  earth  is  much  safer 
than  an  open  bridge,  which,  if  short  and  apparently  insignificant,  may  be,  through  neglect,  a 
most  serious  point  of  danger,  as  was  shown  in  the  dreadful  accident  of  last  yearf  on  the 
Toledo,  Peoria  &  Western  Road  in  Illinois,  where  one  hundred  and  fifty  persons  were  killed 
and  wounded,  and  by  the  equally  avoidable  accident  on  the  Florida  &  Savannah  line  in 
March,  1888.  Had  these  little  trestles  been  changed  to  culverts  covered  with  earth,  many 
valuable  lives  would  not  have  been  lost. 


*  T.  C.  Clarke,  in  Scribner's  Magazine  for  June,  1888,  p.  657. 


t  1887. 


PART  II. 

STANDARD   TRESTLE   PLANS. 

NOTE. — As  the  quantity  of  much  of  the  material  in  a  trestle  varies  with  the  height  and  of  all  of  it  with 
the  length,  it  was  considered  better  to  merely  give  a  list  of  dimensions  of  the  different  parts  rather  than  a 
bill  of  material  for  some  special  height  and  length  in  the  descriptions  of  the  following  examples  of  con- 
struction. 

85 


I* ,9  10 

1* 6'0 

t 


T^TT^W^ — 3  s-r-J&f&zrtt 

' -Si/b 7/  *  3 "  •*  •*•     ^  '^  '  </ 


n  n  n  nn.J~iJ~Ln 


7x6x32'        @ 


3x16x32 


c 
c 


1 


f 


t/l 


n 


SCALE  OF  FEET 

I.,.?    !     ?    ?    ?     5    ?     7     ?    9    '.°   V    '.2 
PLATE  L— STANDARD  PILE-TRESTLE,  DENVER  &  RIO  GRANDE  RAILROAD. 


•    I       fcX 

0^03 
<nV 

II 


86 


PART  II. 

STANDARD    TRESTLE  PLANS. 

SECTION    I. 
PILE    TRESTLES. 

STANDARD  PILE-TRESTLE,  DENVER  &  Rio  GRANDE  RAILROAD. — PLATE  I. 

Dimensions  of  Timber. 

Floor-System  :  Guard-rails,  7  in.  X  8  in.  X  32  ft.,  notched  I  in. 

Ties,  8  in.  X  8  in.  X  12  ft.,  notched  \  in.  for  both  guard-rails  and  stringers, 

as  shown  in  detail. 

Track-stringers,  8  in.  X  16  in.  X  32  ft.,  notched  f  in.  over  caps. 
Jack-stringers,  8  in.  X  16  in.  X  32  ft.,  notched  f  in.  over  caps. 
Bent:  Cap,  12  in.  X  12  in.  X  14  ft.,  notched  f  in.  over  piles. 
Sway-braces,  3  in.  X  10  in. 
Piles,  14  in.  diameter  at  top. 
Bank-bent  :  Dump-boards,  3  in.  X  12  in.  X  14  ft. ;  3  in.  X  12  in.  X  16  ft. ;  3  in.  X  12  in. 

X  18  ft. 
Battens,  3  in.  X  10  in.  X  3  ft. 

Dimensions  of  Iron  Details. 

Bolts :  f  in.  X  33  in. ;  guard-rail  to  ties  and  jack-stringers. 

I  in.  X  38  in.  ;  ties  to  caps. 

I  in.  X  22  in. ;  stringer-joints  ;  packing-bolts. 

I  in.  X  1 8  in. ;  sway-braces  to  posts. 
Drift-bolts :  f  in.  X  22  in.  ;  caps  to  piles. 
Boat-spikes  :  |  in.  X  8  in. ;  sway-braces  to  posts. 
Cast  washers :  f  in.  X  4  in. ;  under  heads  and  nuts  of  f-in.  bolts. 
Cast  separators :  3  in.  X  4  in. ;  between  stringer-pieces  for  f-in.  bolts. 

87 


SCALE  OF  FEET 

1...9    i    ?    ?   1    y   ?    7 


PLATE  II.— STANDARD  PILE-TRESTLE,  TOLEDO,  ST.  LOUIS  &   KANSAS  CITY  RAILROAD. 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES.  89 


STANDARD  PILE-TRESTLE,  TOLEDO,  ST.  Louis  &  KANSAS  CITY  RAILROAD.— PLATE  II. 

Dimensions  of  Timber. 

Floor-system  :  Guard-rails,  6  in.  X  6  in.,  notched  i  in.  over  ties. 
Ties,  6  in.  X  8  in.  X  9  ft. 

Stringers,  7  in.  X  16  in.  X  15  ft.,  notched  i£  in.  over  caps. 
Brace-blocks,  3  in.  X  10  in.  X  15  in. ;  3  in.  X  10  in.  X  3  ft. 
Bents:  Caps,  12  in.  X  12  in.  X  14  ft.,  notched  i  in.  over  piles. 
Sway-braces,  3  in.  X  10  in. 
Piles,  4. 

Bank-bent:  Dump-board,  2  in.  X  10  in.  X  12  ft. 
Cap,  12  in.  X  12  in.  X  12  ft. 
Piles,  3. 

Dimensions  of  Iron  Details. 

Bolts:  f  in.  X  31  in. ;  stringer-joints,  packing-bolts. 

(  guard-rails  to  ties. 
Lag-screws  :  f  in.  X  9  in. ;  \ 

(  ties  to  stringers. 

(  guard-rails  to  ties. 
Boat-spikes  :  f  m.X  8  in. ;  \  * 

(  sway-braces  to  posts. 

,    Drift-bolts :  f  in.  X  20  in. ;  caps  to  piles. 
Wrought  strap :   13  in.  X  2  in.  X  -&  in. ;  stringer-joints. 
Cast  separators :  4  in.  thick  ;  between  stringers. 
Cast  washers :  Under  head  and  nut  of  each  bolt. 
Sheet-iron  :  No.  27,  30  in.  wide ;  to  cover  stringers. 


FIG.  i. — DETAILS  OF  FLOOR-SYSTEMS. 


A,   UP  TO    1 8   FT.   HIGH. 


B,  IQ  TO  26  FT.  HIGH. 
FIG.  2. — PILE-BENTS. 


FIG.  3. — IRON  DETAILS. 


> 


C,    27    TO    32  FT.    HIGH. 

PLATE  III.— STANDARD  PILE-TRESTLES,  ATLANTIC  &  PACIFIC  RAILROAD. 


90 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  9i 


STANDARD  PILE-TRESTLE,  ATLANTIC  &  PACIFIC  RAILROAD.— PLATE  III. 

(See  also  Plate  XXXI.) 
Dimensions  of  Timbers. 

Floor-systems — Fig.  I,  A :  Guard-rails,  6  in.  X  6  in.  X  16  feet. 

Ties,  6  in.  X  8  in.  X  9  ft. 
Stringers,  7  in.  X  16  in.  X  15  ft. 
Brace-blocks,  2  in.  X  10  in.  X  18  in. 
Fig.  i,  B:  same  as  above. 
Bents:  Caps,  12  in.  X  14  in.  X  14  ft. 
All  sway-braces,  3  in.  X  10  in. 
Piles,  12  in.  diameter. 

Dimensions  of  Iron  Details. 

Floor-system — Fig.  I,  B;  Four-piece  stringer: 

Bolts,  f  in.  X  46  in. ;  stringer-joints. 

Packing-bolts,  f  in.  X  30  in. ;  guard-rails  to  stringers. 

Splice-plates  :  if  in.  X*  4  in.  X  10  in. ;  stringer-joints. 

Cast  separators  :  4  in.  X  4i  in. ;  between  stringer-pieces ;  f-in. 

bolts. 

Cast  washers :  f  in.  X  4i  in. ;  under  head  and  nut  of  each  bolt. 
Spikes :  Boat,  f  in.  X  f  in.  X  7  in. ; 

Cut  2o-penny. 

Three-piece  stringer :  Bolts,  f  in. ;  X  34  in. ;  stringer-joints  ;  pack- 
ing-bolts. 

f  in.  X  30  in. ;  guard-rails  to  stringers. 
Splice-plates,  as  above. 
Cast  separators,  as  above. 
Cast  washers,  as  above. 
Spikes :  Boat,  as  above.     Cut,  as  above. 
Bents :  Bolts,  f  in.  X  20  in. ;  sway-braces  to  piles. 

Drift-bolts :  f  in.  X  t  in.  X  22  in. ;  caps  to  piles. 

Boat-spikes  :  f  in.  X  I  in.  X  7  in. ;  sway-braces  to  piles. 

Cast  washers:  f  in.  X  4i  in. ;  under  head  and  nut  of  each  bolt. 


Fir,,  i.— PILE-TRESTLE. 


FIG.  2. — DETAILS  OF  SEPARATOR  AND  CAST  WASHERS 


PLATE  IV.— STANDARD  PILE-TRESTLE,  CHICAGO  &  WEST  MICHIGAN  RAILWAY. 


92 


A    TREATISE   ON    WOODEN    TRESTLE   BRIDGES. 


93 


STANDARD  PILE-TRESTLE,  CHICAGO  &  WEST  MICHIGAN  RAILWAY. — PLATE  IV. 

(See  also  Plate  X.) 

Dimensions  of  Timbers, 

Floor-system:  Guard-rails,  8  in.  X  10  in.,  notched  2  in.  over  ties. 

Ties,  6  in.  X  8  in.  X  12  ft.,  notched  \  in.  over  stringers. 
Stringers,  6  in.  X  16  in.  X  24  ft. 
Bent  :  Cap,  12  in.  X  12  in.  X  14  ft. 
Sway-braces,  3  in.  X  12.  in. 
Piles,  12  in.  diameter. 
Bank-bent:  Dump-plank,  3  in.  X  12  in.  X  16  ft. 

Dimensions  of  Iron  Details. 

Bolts:  f  in.  X  32  in.;   guard-rails  to  stringers. 

fin.  X  i6£  in.;  stringer-joints;  packing-bolts. 

f  in.  X  1 8  in.  ;  sway-braces  to  piles. 
Drift-bolts:   fin.  X  24  in.  ;  stringers  to  caps. 
Boat-spikes :  f  in.  X  7  in. ;  sway-braces  to  piles. 
Cast  washers:  f  in.  X  in.  3^  in.  ;  under  head  and  nut  of  each  bolt. 
Other  dimensions  as  per  following  table  : 


BOLT. 

A 

B 

C 

D 

E 

F 

G 

WEIGHT. 

f-r 

1" 

V 

I" 

3*" 

2" 

t" 

Ty 

it  Ibs. 

.t  -i" 

I" 

It" 

It" 

5" 

2f 

f" 

f 

it  -it" 

It" 

If" 

It" 

6" 

3" 

1" 

TV 

it  —it" 

It" 

If 

If 

7t" 

3t 

t" 

f 

it  —if 

If" 

It" 

2" 

8t" 

4t 

i" 

*' 

It  -2" 

2" 

-2t" 

2i" 

9t" 

5" 

it" 

i' 

Cast  separators :  3  in.  X  2  in.  thick ;  between  stringer-pieces. 
These  trestles  are  built  with  spans  of  12  ft.,  14  ft.,  and  16  ft. 


SCALE  OF  FEET 
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JGross  Section,  ' 


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Floor  System 

PLATE  V.— STANDARD  PILE-TRESTLE,  MINNEAPOLIS  &  ST.  LOUIS  RAILWAY. 


94 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  95 


STANDARD  PILE-TRESTLE,  MINNEAPOLIS  &  ST.  Louis  RAILWAY. — PLATE  V. 

(See  also  Plate  XXII.) 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rail,  6  in.  X  8  in.,  notched  2  in.  over  ties. 
Ties,  6  in.  X  8  in.  X  10  ft.,  white  oak. 
Stringers,  6  in.  X  16  in.  X  15  ft.  6  in. 

Packing-block,  6  in.  X  16  in.  X  5  ft.  4  in.,  notched  2  in.  over  caps. 
Bent:  Cap,  12  in.  X  14  in.  X  14  ft.,  laid  flat. 
Sway-braces,  3  in.  X  12  in. 
Piles,  not  less  than  1 1  in.  diameter. 
Bank-bent  :  Dump-plank,  old  stringers. 

Dimensions  of  Iron  Details. 

Bolts  :  f  in.  X  41  in. ;  stringer-joints  ;  packing-bolts. 
Lag-screws  :  Stringer-brackets  to  caps. 
Spikes  :  Boat,  £  in.  X  8  in.;  guard-rails  to  ties. 
Drift-bolts  :  |  in.  X  12  in.;  ties  to  stringers. 

\  in.  X  22  in.;  caps  to  piles. 

Cast  separators  :  2  in.  wide  ;  between  packing-blocks  and  stringers. 
Cast  washers  :  Under  head  and  nut  of  each  bolt. 
Cast  brackets  :  Stringers  to  caps. 

For   arguments   in  favor  of  and  description  of  this  trestle,  see  Railroad  Gazette,  April 
17,  1891. 


JO'O 


KM 


Casf spool 'for  Vt  "6o(t 


Corbel-stringer 
Separator. 


Angle-lug. 


Cast-iron  Spool. 


IRON  DETAILS. 


DETAILS  OF  STRINGER-JOINT. 
PLATE   VI.— STANDARD    PILE-TRESTLE,    CHICAGO    cS:    NORTHWESTERN    RAILWAY. 


96 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  97 


STANDARD  PILE-TRESTLE,  CHICAGO  &  NORTHWESTERN  RAILWAY. — PLATE  VI. 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rails,  8  in.  X  8  in.  X  16  ft.,  notched  I  in.  over  ties. 
Ties,  6  in.  X  8  in.  X  12  ft.,  white  oak. 
Track-stringers.  10  in.  X  14  in.  X  16  ft. 
Jack-stringers :   10  in.  X  14  in.  X  16  ft. 
Corbels,  10  in.  X  10  in.  X  5  ft.  4  in.,  notched  I  in.  over  cap,  and  used  only 

on  bridges  of  two  spans  or  over. 
Bents  :  Cap,  12  in.  X  14  in.  X  14  ft. 
Sway-braces,  3  in.  X  10  in. 
Piles,  12  in.  diameter. 

f  3  in.  X  10  in.  X  16  ft. ; 
Bank-bent:  Dump-plank,  \  3  in.  X  12  in.  X  14  ft.; 

L  3  in.  X  12  in.  X  16  ft. 
2  in.  X  4  in.  X  34  in-; 


Battens, 

'  2  in.  X  4  in.  X  22  in. 

Number-boards  :   i^  in.  X  8  in.  X  12  in. 


Dimensions  of  Iron  Details. 

Bolts:  f  in.  X  2  ft.  3  in.;  stringer-joints  ;  packing-bolts;  also  stringers  to  corbels. 

f  in.  X  2  ft.  5!  in.;  guard-rails  to  stringers. 

|  in.  X  3  ft.  4!  in.;  guard-rails  to  corbels. 

f  in.  X  19!  in.;  sway-braces  to  caps  and  piles. 
Dowels  :   i  in.  X  21  in.;  caps  to  piles. 
Spikes  :  Boat,  T5¥  in.  X  5  in. 

Cut  3O-penny. 
Cast  separators  :  3  in.  X  4  in. ;  as  per  detail  drawing  ;  between  stringer-pieces. 

6  in.  X  10  in. ;  as  per  detail  drawing ;  between  stringers  and  corbels, 
Cast  washers  :  Under  head  and  nut  of  each  bolt. 
Angle-iron  lugs :  2  in.  x  3i  in.  L  X  4  in.  long  ;  hold  stringers  in  place. 


1 


fr-EM-^^^ 

gnu-~-..- I£DK., 


FIGS,  i,  2.— FOR  HEIGHTS  OF  5  FT.  OR  UNDER.  FIG.  3.— FOR  HEIGHTS  ABOVE  24  FT. 

PLATE  VII.— STANDARD    PILE-TRESTLE,  LOUISVILLE   &   NASHVILLE    RAILROAD. 


n 

T  ,*  

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1  1  II  1  1  1  1 

Plan  ,   omitting  Hills  end  Ties. 
d 

V  ....-?..  i  .f 


PLATE  VIII.— PILE-TRESTLE  WITH  EARTH  ROADBED,  LOUISVILLE  &  NASHVILLE  RAILROAD. 

98 


A    TREATISE  ON    WOODEN    TKESTLE  BRIDGES.  99 

STANDARD  PILE-TRESTLE,  LOUISVILLE  &  NASHVILLE  RAILROAD. — PLATE  VII. 

(See  also  Plates  VIII  and  XVII.) 

Dimensions  of  Timbers. 
Floor  System  :  Guard-rails,  outside,  5  in.  X  9  in.,  notched  I  in.  over  ties. 

inside,  4  in.  X  9  in.,  not  notched. 
Ties,  6  in.  X  8  in.  X  9  ft. 
Stringers,  8  in.  X  16  in.  X  30  ft. 

Corbels,  8  in.  X  i6f  in.  X  3  ft.,  notched  I  in.  over  caps. 
Bents  :  Caps,  12  in.  X  14  in.  X  12  feet. 

Sway-braces,  diagonal,  2\  in.  X  10  in. 
horizontal,  4  in.  X  10  in. 
Piles,  12  in.  diameter. 
Girts  :  6  in.  X  8  in.  X  30  ft. 
Splice-blocks  :  2  in.  X  8  in.  X  3  ft. 

Dimensions  of  Iron  Details. 

Bolts:  |  in.  X  27  in.;  stringers  to  corbels.' 

\  in.  X  19^  in.;  stringer-joints  ;  packing-bolts, 
f  in.  X  42  in. ;  floor-system  to  caps. 
Drift-bolts  :  f  in.  x  22  in.;  caps  to  piles. 
Dowels  :  f  in.  X  5  in.;  ties  to  stringers. 
Spikes  :  |  in.  x  9  in.;  corbels  to  caps. 

£  in.  x  8  in.;  horizontal  sway-braces  to  piles. 

\  in.  X  7  in. ;   diagonal  sway-braces  to  piles. 

J  in.  X  12  in. ;  girts  to  piles. 
Lag-screws  :  f  in.  X  7  in.;  guard-rails  to  ties. 
Cast  washers  :  Under  head  and  nut  of  each  bolt. 
Cast  separators  :  Between  stringer-pieces. 

PILE-TRESTLE  WITH  EARTH  ROADBED,  LOUISVILLE  &  NASHVILLE  RAILROAD.— 
PLATE  VIII.     (See  also  Plates  VII  and  XVII.) 

Dimensions  of  Timbers. 
Ties,  6  in.  X  12  in.  X  10  ft. 
Side-timbers,  6  in.  X  12  in.  X  32  ft. 
Floor-timbers,  8£  in.  X  12  in.  x  32  ft. 
Caps,  6  in.  X  15  in.  X  14  ft. 
Sway-bracing,  3  in.  x  10  in. 
Piles,  12  in.  diameter. 
Revetment-timbers,  12  in.  x  12  in. 

All  timber  creosoted  yellow  pine,  spiked  together.     No  bolts  or  mortise  and  tenon  joints 
used. — Eng.  News,  Oct.  29,  1887. 


VI* 


aaf-- 


U 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  101 


STANDARD  PILE-TRESTLE,  BOSTON  &  ALBANY  RAILROAD. — PLATE  IX. 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rails,  12  in.  X  12  in.,  notched  if  in.  over  ties. 

Ties,  10  in.  X  IO  in.  X  12  ft.,  notched  \\  in.  over  stringers. 
Stringers,  6  in.  X  H  in.  X  30  ft. 
Corbels,  6  in.  X  7  in.  X  6  ft. 
Bents:  Caps,  6  in.  X  12  in.  X  12  ft.  6  in. 
Sway-braces,  3  in.  X  12  in. 
Piles,  12  in.  diameter. 
Lateral  braces  :  6  in.  X  6  in. 

Dimensions  of  Iron  Details. 

Bolts  :  |  in.  X  23^  in. ;  guard-rails  to  ties. 

|  in.  X  16  in.  ;  stringer-joints;  packing-bolts. 

f  in.  X  21  in. ;   caps  to  piles. 

\  in.  X  132  in. ;  lateral  brace  intersections. 
Spikes. 

Cast  separators. 
Cast  washers. 


rr   Jl 


ZJO  i 

\  •-•-'  f 

p 

f 

PLATE  X.— STANDARD   FRAMED   TRESTLE,  CHICAGO  &  WEST   MICHIGAN   RAILWAY. 

102 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  103 


SECTION   II. 
FRAMED   TRESTLES. 

STANDARD  FRAMED  TRESTLE,  CHICAGO  &  WEST  MICHIGAN  RAILWAY.— PLATE  X 

(See  also  Plate  IV.) 

Dimensions  of  Timbers. 

Floor-system  :    Guard-rails,  8  in.  X  10  in.,  notched  2  in.  over  ties. 

Ties,  6  in.  X  8  in.  X  12  ft.,  notched  £  in.  over  stringers. 
Stringers,  8  in.  X  16  in.  X  32  ft. 
Bent:  Cap,  12  in.  X  12  in.  X  14  ft. 
Plumb-posts,  12  in.  X  12  in. 

Batter-posts,  12  in.  X  12  in. ;  batter,  2  in.  to  I  ft. 
Sill,  12  in.  X  12  in. 
Sway-braces,  3  in/X^  12  in. 
Sub-sills,  12  in.  X  12  in    X  6  ft 

Dimensions  of  Iron  Details. 
Same  as  for  Plate  IV 


SFee 


3/o spifte  9  /one 
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10    1    2    3    4  5  6  7    8  3  10  Feef 
Scale  for  fresffes. 

PLATE   XL— STANDARD    FRAMED   TRESTLES,    PENNSYLVANIA    RAILROAD. 


IOA 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES. 


STANDARD  FRAMED  TRESTLE,  PENNSYLVANIA  RAILROAD. — PLATE  XL 

Dimensions  of  Timbers. 

Floor-system :   Guard-rails,  5  in.  X  8  in.,  notched  I  in.  over  ties. 

Ties,  7  in.  X  10  in.  X  9  ft.,  notched  \  in.  to  receive  guard  rails,  and  £  in. 

over  stringers. 
Stringers  : 


Clear  Span. 

Number  of  Pieces 
under  each  Rail. 

Width  of 
each  Piece. 

Depth  of 
Stringers. 

10  ft. 
12    " 

2 
2 

8  in. 
8   " 

15  in. 
16   " 

14   " 
16    " 

2 

3    - 

10    " 

8   " 

17   " 

17   • 

Packing-blocks,  2  in.  X  18  X  6  ft. 
Bents  under  20  ft. :  Cap,  10  in.  X  12  in.  X  10  ft. 
Plumb-posts,  10  in.  X  12  in. 
Batter-posts,  10  in.'X  10  in.;  batter,  3  in.  to  I  ft. 
Sill,  10  in,  X  12  in. 

Bents  20  ft,  and  over:  Cap,  12  in.  X  14  in.  X  12  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  10  in.  X  12  in.,  batter  3  in.  to  I  ft. 
Sill,  12  in.  X  12  in. 
Sway-bracing,  3  in.  X  10  in. 
Bracing :  Longitudinal,  8  in.  X  8  in. 
Treenails :  Locust,  I  in.  diameter. 


in.  X- 
in.  X- 
in.  X- 


Dimensions  of  Iron  Details. 

Bolts:  1  in.  X—   — ;   guard-rails  to  ties. 
•;    guard-rail  joints. 
- ;    stringer-joints  ;  packing-bolts. 
All  of  above  bolts  have  2^-in.  flat  heads,  with  2^-in.  wrought  washer  .under 
nuts. 

f  in.  X ,  sway-bracing  to  caps  and  sills;   3-in.  wrought-iron  washers  used. 

Drift-bolts  (ragged):   i  in.  X  24  in.;  stringers  to  caps. 
Spikes :  Boat?  %  in.  X  9  in. ;  guard-rails  to  ties. 

£  in.  X  8  in. ;  sway-braces  to  posts. 

Cut  -    —  X ,  longitudinal  braces  to  caps  and  sills. 

Wrought  washers :  2\  in.  square  for  f-in.  bolt. 
3  in.  round  for  f-in.  bolt.. 


7   S'/s 


r"  ^_^  .oietio'- 


PLATE  XII.— STANDARD   FRAMED   TRESTLE,    SAN   FRANCISCO   &    NORTH    PACIFIC    RAILROAD. 

106 


A    TREATISE  ON    WOODEN  TRESTLE  BRIDGES. 


107 


,£x  8 


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I  | 

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DETAILS  OF  FLOOR-SYSTEM. 
PLATE  XIII.— STANDARD  FRAMED  TRESTLE,  SAN   FRANCISCO  &  NORTH    PACIFIC   RAILROAD. 


STANDARD  FRAMED  TRESTLE,  SAN  FRANCISCO  &  NORTH  PACIFIC  RAILROAD. 

PLATES  XII  AND  XIII. 

Dimensions  of  Timbers. 
Floor-system  :  Guard-rails,  6  in.  X  8  in.,  notched  over  ties. 

Ties,  8  in.  X  8  in.  X  10  ft.,  notched  over  stringers. 
Stringers,  7  in.  X  16  in.  X  31  ft.  5^  in.,  notched  i  in.  over  caps. 
Bents:  Caps,  12  in.  X  12  in.  X  14  ft. 
Plumb-posts,  12  in.  X  12  in. 

Batter-posts,  12  in.  X  12  in.;  batter,  3  in.  to  i  ft 
Sill,  12  in.  X  12  in. 
Sway-braces:  Horizontal,  4  in.  X  8  in. 

Diagonal,  4  in.  X  8  in.,  4  in.  X  10  in.,  4  in.  X  12  in. 
Longitudinal  bracing :  Girts,  6  in.  X  8  in. 
Sub-sills:  6  in.  X  12  in.  X  3  ft. 
Bank-bent:  Dump-boards,  3  in.  X  12  in.  X  14  ft. 

Dimensions  of  Iron  DetaUs. 
Bolts :  f  in.  X  37  in. ;  floor-system  to  cap. 

|  in.  X  36  in. ;  stringer  joints ;  packing  bolts. 

•|  in.  X  28^  in. ;  guard-rails  to  ties  and  stringers. 

f  in.  X  2i£  in.;  horizontal  sway-braces  to  posts. 

f  in.  X  18^  in. ;  longitudinal  braces  to  posts. 

•|  in.  X  17^  in.  ;  diagonal  sway-braces  to  posts,  etc. 

Drift-bolts  : X ;  cap  to  posts. 

X ;  sill  to  piles. 

Spikes  :  8  in. ;  sway-braces  to  posts,  etc. 

Cast  separators:  4  in.  X  6  in.  thick;  between  stringer-pieces. 

Cast  washers  for  f-in.  and  f-in.  bolts. 


SCALE  OF  FEET 
Hp]  2345^7891^          ,1,6,  ,   ,  ,20 

FIG.  i.— CROSS-SECTION.  FIG.  2.— ELEVATION. 

GENERAL  PLAN  SINGLE-DECK  TRESTLES. 


FIG.  3. — PLAN  FOR  BREAKING  SILLS  AND  STEPPING  FOOTINGS  ON  STEEP  SLOPES. 
PLATE  XIV.— STANDARD  TRESTLES,  NORFOLK  &  WESTERN  RAILROAD. 


108 


fftetfi. 


SSSW$$$^mS$S«^^ 


SCALE  OF  FEET 


OI2345  JO          15         20 


FIG.  4. — CROSS-SECTION  HIGH  OR  MULTIPLE  STORY  TRESTLE. 
PLATE   XV.— STANDARD   TRESTLE,    NORFOLK   &    WESTERN    RAILROAD. 


tog 


W/ien  fewer  sfbry  ytouM   — 
ie  /ess  than  /S/7  in  clear     . 


FIG.  5. — ELEVATION  HIGH  OR  MULTIPLE  STORY  TRESTLE. 
PLATE  XVI.— STANDARD   TRESTLE,    NORFOLK   &   WESTERN    RAILROAD. 


no 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  in 


STANDARD   FRAMED   TRESTLE,  NORFOLK   &   WESTERN    RAILROAD. 
PLATES  XIV,  XV,  AND  XVI. 

PLATE   XIV. 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rails,  6  in.  X  8  in.,  notched. 
Ties,  8  in.  X  8  in.  X  10  ft.,  notched. 
Stringers,  7  in.  X  15  in.  X  25  ft. 

Packing-blocks,  2  in.  X  15  in.  X  3  ft.,  notched  I  in.  over  cap. 
Bent :  Cap,  6  in.  X  12  in.  X  10  ft. 
Plumb-posts,  12  in.  X  12  in. 

Batter-posts,  10  in.  X  12  in. ;  batter,  2\  in.  to  I  ft. 
Sill,  10  in.  X  12  in. 
Sway-bracing:  Diagonal,  2  in.  X  10  in. 

Horizontal,  2  in.  X  10  in. 
Longitudinal  bracing:  Horizontal,  4  in.  X  12  in.  X  15  ft.  6  in. 

Diagonal,  3  in.  X  12  in. 
Sub-sills:  4  in.  X  12  in.  X  2  ft.  6  in. 

PLATES   XV   AND   XVI. 

Floor-system  :  Guard-rails,  6  in.  X  8  in. 

Ties,  8  in.  X  8  in.  X  14  ft. 
Stringers,  6  in.  X  14  in.  X  25  ft. 
Packing-blocks,  2  in.  X  14  in.  X  5  ft. 
Corbels,  8  in.  X  1 1  in.  X  5  ft. 
Bent:  Cap,  6  in.  X  12  in.  X  10  ft. 
Plumb-posts,  12  in.  X  12  in. 

Outside  batter-posts,  10  in.  X  12  in.,  and  12  in.  X  12  in. 
Inside  batter  posts,  8  in.  X  12  in.,  and  10  in.  X  12  in. 
Sway-braces,  2  in.  X  10  in. 
Intermediate  caps,  6  in.  X  12  in. 
Sill,  10  in.  X  12  in. 
Longitudinal  bracing:  Horizontal,  4  in.  X  12  in.  X  28  ft. 

Diagonal,  3  in.  X  12  in. 

Knee-braces  :  Straining-beam,  10  in.  X  10  in.  X  9  ft. 
Top  chord,  10  in.  X  10  in.  X  6  ft.  4  in. 
Bottom  chord,  5  in.  X  12  in.  X  28  ft. 
Diagonals,  10  in.  X  10  in. 
For  method  of  elevating  rails  on  curves,  see  Part  I,  Fig.  125. 


FIG.  i. — GENERAL  PLANS. 


• 


W1V*.       (Ste" 


FIG.  3. — DETAIL  OF  JOINT  OF 
DIAGONAL  POSTS. 


FIG.  2  —DETAILS  OF  STRINGER 
AND  POST  JOINTS. 

PLATE  XVII.— STANDARD  FRAMED  TRESTLE,  LOUISVILLE  &   NASHVILLE  RAILROAD. 

112 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES.  113 


STANDARD  FRAMED  TRESTLE,  LOUISVILLE  &  NASHVILLE  RAILROAD. — PLATE  XVII. 

(See  also  Plates  VII  and  VIII.  ) 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rails,  3  in.  X  9  in. 
Ties,  8  in.  X  8  in.  X  10  ft. 
Stringers,  8  in.  X  16  in.  X  30  ft. 
Corbels,  8  in.  X  i6f  in.  X  3  ft. 
Bent:  Cap,  12  in.  X  12  in.  X  12  ft. 
Batter-posts,  12  in.  X  12  in. 

Diagonal  posts,  8  in.  x  10  in.,  notched  2  in.  each  at  intersection. 
Intermediate  cap,  6  in.  X  10  in. 
Sill,  12  in.  X  12  in. 
Longitudinal  braces :  Horizontal,  8  in,  x  10  in.  x  30  ft. 

Splice-block,  4  in.  x  12  in. 
Sub-sills:  12  in.  X  12  in.  X  6  ft. 

Dimensions  of  Iron  Details. 

Bolts :  |  in.  X  27  in.;  stringers  to  corbels  and  intermediate  cap  to  posts. 

£  in.  X  20  in.  ;  stringer-joints ;  packing-bolts. 

f  in.  X  15  in. ;  splice-block  to  girts. 

£  in.  X  23  in. ;  angle-block  to  posts. 
Spikes :  |  in.  X  14  in. ;  corbels  to  caps. 
Dowels :  |  in.  X  5  in.  ;  diagonal  posts  to  angle-blocks. 
Cast  washers :  Under  head  and  nut  of  each  bolt. 
Cast  separators :  f  in.  X ;  between  stringer-pieces. 


SCALE  OF  FEET 
1012345678810  f    [   IS^  |  2O  f 


FIG.  i. — CROSS-SECTION. 


FK;.  2. — ELEVATION. 


[3         .  g 


-m-jiF        ~*~"lT 
is1 1 

FIG.  3. — FLOOR-SYSTEM. 


FIG.   5. — DKTAILS  OF  WALLS  AND  GIRTS. 


PLATE    XVIII.— STANDARD    FRAMED    TRESTLE, 
OREGON    PACIFIC    RAILROAD. 

114 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES. 


STANDARD  FRAMED  TRESTLE,  OREGON  PACIFIC  RAILROAD. — PLATE  XVIII. 

Dimensions  of  Timbers. 
Floor-system  :  Guard-rails,  6  in.  X  8  in.,  notched  \\  in. 

Ties,  8  in.  X  8  in.  X  9  ft.,  not  notched  ;  and  two  ties  13  ft.  long  for  every 

fourth  span  projecting  on  alternate  sides. 
Stringers,  10  in.  X  16  in.  x  16  ft.,  not  notched. 
Bent:  Caps,  12  in.  X  12  in.  X  12  ft. 

Plumb-posts,  12  in.  X  12  in.,  in  23  ft.  6  in.  lengths. 
Outside  batter-posts,  12  in.  x  12  in.,  in  24  ft.  oTV  in.*  lengths. 
Counter-posts  or  inside  batter-posts,  10  in.  x  12  in.,  in  24  ft.  oTy*  in.  lengths. 
Intermediate  caps  or  horizontal  sway-bracing,  6  in.  X  14  in. 
Diagonal  sway-bracing,  4  in.  x  10  in. 
Sill,  12  in.  X  12  in. 
Longitudinal  bracing:  Girts,  6  in.  X  10  in.  X  18  ft.,  notched  i£  in. 

Diagonals,  8  in.  X  10  in.,  sized  to  6  in.  at  posts. 
Packing-pieces,  8  in.  thick  at  intersection  of  diagonals. 

Dimensions  of  Iron  Details. 

Bolts :  f  in.  X  14  in. ;  guard-rails  to  ties. 

f  in.  X  30  in. ;  through  guard-rails,  ties,  and  outside  stringers. 

|  in.  X  27  in. ;  ties  to  stringers. 

f  in.  X  31  in. ;  stringers  to  caps. 

f  in.  X  48  in.  ;  stringer-joints ;  packing-bolts. 

f  in.  X  1 8  in.  ;  diagonal  sway-braces  to  posts. 

|  in.  X  28  in. ;  ] 

f  in.  X  22  in. ; 

•  bolt  at  joint  H  and  its  companion  joint. 
|  in.  X  24  in. ; 

f  in.  X  31  in. ; . 

f  in.  X  24  in. ;  intermediate  caps  to  posts. 
|  in.  X  1 8  in. ;  sill-joint  bolts. 
|  in.  X  22  in.  ; 


,  girt-bolts. 
|  in.  X  24  in. ; (  & 

f  in.  X  21  in. ;  diagonal  longitudinal  braces  to  posts. 

f  in.  X  27  in. ;  intersection  of  above. 
Dowels :  f  in.  X  8  in. ;  cap  and  sill  to  posts ;  post-joints. 

Drift-bolts:  X  — 

Cast  washers :  Under  heads  and  nuts  of  each  bolt. 
Cast  separators :   i^  in.  x ;  between  stringer-pieces. 


*  So  in  original  blue  print,  but  rather  too  close  to  work  to  in  this  size  timber. 


Xttf* 


m 


PLATE  XIX.— FRAMED   TRESTLE,    OHIO   CONNECTING    RAILWAY. 


1X6 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  117 


FRAMED  TRESTLE,  OHIO  CONNECTING  RAILWAY. — PLATE  XIX. 

Dimensions  of  Timbers. 
Floor-system  :  Guard-rails,  6  in.  X  8  in.,  notched  f  in.  over  ties. 

Ties,  7  in.  X  8  in.  X  10  ft.,  notched  f  in.  over  stringers. 
Stringers,  7  in.  X  14  in.  X  24  ft. 
Corbels,  10  in.  X  15  in.  X  5  ft.,  notched  over  caps. 
Bents:  Caps,  12  in.  X  12  in.  X  12  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in. 
Counter-posts,  12  in.  X  12  in. 
Intermediate  caps,  12  in.  X  12  in. 
Sills,  12  in.  X  12  in. 
Longitudinal  braces,  8  in.  X  12  in.  X  14  ft. 


FIG.  i. — CROSS-SECTION. 


FIG.  2.— ELEVATION. 


FIG.  5. — PACKING- 
WASHER. 


TT 


n  nl  n  n 


u  u  u 


SCALE  OF  FEET 


I    OI23466789IO  16 20 48 69 


Fic.  4. — SECTION  A  B,  SHOWING  BRACING  IN  EMBANKMENT.  FIG,  3, — PLAN, 


S£ 
— ^.iaK/av-^'-gg^""^  '     17.^*^1  l^i  ••or.rd.it  eo\  v»J,f  -^ .  MI  tea — rjr 
• 

FIG.  6. — DOUBLE-DECK  TKESTI.E.  FIG.  7.— TRIPLE-DECK  TRESTLE. 


T  v 

f 


PLATE   XX.— PRESENT    STANDARD    T.RESTLE,    CHARLESTON,    CINCINNATI    &    CHICAGO 

RAILROAD. 

1x8 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  119 


STANDARD  FRAMED  TRESTLE,  CHARLESTON,  CINCINNATI  &  CHICAGO  RAILROAD. 

PLATES  XX  AND  XXI. 


PLATE  XX. 

Dimensions  of  Timbers. 

Floor-system  :   Guard-rails,  6  in.  X  8  in.  X  16  ft. 
Ties,  7  in.  X  8  in.  X  10  ft. 
Stringers,  7  in.  x  16  in.  X  30  ft.  and  15  ft. 
Bent-  Cap,  12  in.  X  12  in.  X  12  ft. 
Plumb-posts,  \2  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in. 
Sway-bracing,  3  in.  X  10  in. 
Intermediate  cap,  12  in.  X  12  in. 
Sill,  12  in,  X  12  in. 
Longitudinal  bracing :  Horizontal,  6  in.  X  8  in.  X  16  ft. 

Diagonal,  4  in.  X  10  in. 
Sub-sills,  loin.  X  12  in.  X  6ft. 

Dimensions  of  Iron  Details. 
Bolts:  |  in.  X  15  in. ;  guard-rails  to  ties. 

|  in.  X  1 8  in. ;  sway-braces  to  posts. 
|  in.  X  28  in.  ;  stringer-joints ;  packing-bolts. 
Drift-bolts  :  f  in.  X  I  in.  X  20  in. ;  sills  to  sub-sills. 

|  in.  X  f  in.  X  24  in. ;  stringers  to  caps  ;  caps  to  posts. 
Dowels:  f  in.  X  8  in. ;  posts  to  sills. 
Spikes,  boat  :  f  in.  X  8  in. ;   girts  to  posts. 

\  in.  X  10  in. ;  ties  to  stringers. 

Cast  separators  :  2  in.  x  3  in, ;  between  stringer-pieces. 
Cast  washers  :  -      -  X  3  in.  ;  under  head  and  nut  of  each  bolt. 


FIG.  i. — CROSS-SECTION.  FIG.  3. — PLAN. 

SINGLE-DECK  TRESTLE. 


SCALE  OF  FEET 
0  |  2345 10  15  20  2^ 

FIG.  4. — CROSS-SECTION.  FIG.  5. — ELEVATION. 

TRIPLE-DECK  TRESTLE. 

PLATE  XXI.— FORMER  STANDARD  TRESTLE,    CHARLESTON.  CINCINNATI  &  CHICAGO  RAILROAD 

i  bo 


A    TREATISE   ON    WOODEN   TRESTLE  BRIDGES.  121 


PLATE  XXI. 

Dimensions  of  Timbers. 
Floor-system  :    Guard-rails,  6  in.  X  8  in. 

Ties,  7  in.  X  8  in.  X  10  ft. 
Stringers,  6  in.  X  14  in.  X  30  ft.  and  15  ft. 
Corbels,  12  in.  X  18  in.  X  6  ft. 
Bent:  Cap,  12  in.  X  12  in.  X  12  ft. 
Posts,  12  in.  X  12  in. 
Intermediate  caps,  12  in.  X  12  in. 
Sway-braces,  2  in.  X  12  in. 
Sill,  12  in.  X  12  in. 
Longitudinal  braces  :  Horizontal,  6  in.  X  12  in.  X  16  ft. 

Diagonal,  6  in.  X  8  in. 
Sub-sills,  12  in.  X  12  in.  X  6  ft. 

Dimensions  of  Iron  Details. 
Bolts  :  fin.  X  15  in. ;  guard-rails  to  ties, 
f  in.  X  19  in. ;  stringers  to  corbels, 
fin.  X  21  in.;  stringer-joints;  packing-bolts, 
f  in.  X  27  in.  ;  longitudinal  braces  to  posts,  and  post-caps  to  intermediate  caps. 

-  X  15  in.  ;  intersection  of  diagonal  longitudinal  braces. 
Drift-bolts  :  f  in.  X  f  in.  X  18  in. ;  corbels  to  cap. 
Spikes  :  Boat,  T\  in.  X  10  in. ;  ties  to  stringers. 

Cut  5<D-penny  ;  bracing  to  posts. 
Cast  washers :  Under  head  and  nut  of  each  bolt. 


PLATE   XXII.— HIGH   FRAMED    TRESTLES,   MINNEAPOLIS   &   ST.    LOUIS    RAILWAY. 


A    TREATISE  ON    WOODEN   TRESTLE   BRIDGES.  123 


HIGH  FRAMED  TRESTLES,  MINNEAPOLIS  &  ST.  Louis  RAILWAY.— PLATE  XXII. 

(See  also  Plate  V.) 

Dimensions  of  Timbers. 
Floor-system  :  Guard-rails,  6  in.  X  8  in. 

Ties,  6  in.  X  8  in.  X  10  ft. 
Stringers,  8  in.  X  14  in.  X  30  ft. 
Bent:  Cap,  12  in.  X  12  in.  X  14  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in. 
Sway-bracing:    Horizontal,  3  in.  X  12  in. 

Diagonal,  3  in.  X  12  in. 
Intermediate  cap,  12  in.  X  12  in. 
Sill,  12  in.  x  12  in. 
Sill-splice,  12  in.  x  12  in. 

Longitudinal  braces:  Horizontal,  3  in.  x  12  in. 
Diagonal,  3  in.  x  12  in. 

Dimensions  of  Iron  Details. 

Bolts :  |  in.  X  ;  stringer-joints  ;  packing-bolts. 

X ;  braces  to  posts. 

Lag-screws  : X ;  stringer-brackets  to  caps. 

Spikes,  boat :  \  in.  X  8  in. ;  guard-rails  to  ties. 

Drift-bolts  :  |-  in.  X  12  in. ;  ties  to  stringers. 

Cast  separators  :  Between  stringer-pieces. 

Cast  washers  :  Under  head  and  nut  of  each  bolt. 

Cast  brackets :  Stringers  to  caps. 

Cast  pile-caps:  ^ 

Cast  post-caps :  V  As  per  details. 

Cast  post  foot-blocks  :  J 

For  complete  description,  etc.,  of  this  trestle  see  Railroad  Gazette,  April  17,  1891. 


w 


8- 


OH 


X33J  JO  31VOS 


124 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  125 


STANDARD  FRAMED  TRESTLE,  GEORGIA  PACIFIC  RAILWAY. — PLATE  XXIII. 

Dimensions  of  Timbers. 
Floor-system  :  Guard-rails,  8  in.  X  8  in. 
Ties,  8  in.  X  10  in.  X  9  ft. 
Stringers,  8  in.  X  16  in. 
Bent:  Cap,  12  in.  X   12  in.  X  II  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in.,  and  10  in.  X  12  in. 
Vertical  counter-posts,  10  in.  X  12  in. 
Intermediate  caps  and  sills,  12  in.  X  12  in. 
Compound  sills  and  caps,  4^  in.  X  12  in.,  and  2\  in.  X  12  in. 
Longitudinal  bracing :  Horizontal,  4  in.  X  10  in.  X  16  ft.  4  in.,  and  7  in.  X  IO  in.  X  16  ft. 

Diagonal,  3  in.  X  10  in. 
Sub  sills,  12  in.  X  12  in. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  127 


STANDARD  FRAMED  TRESTLES,  OREGON  &  WASHINGTON  TERRITORY  RAILROAD.- 

PLATE  XXIV. 

Dimensions  of  Timbers. 

Floor-system:  Guard-rails,  10  in.  X  12  in.,  and  5  in.  X  8  in. 
Ties,  6  in.  X  8  in.  X  16  ft. 
Track-stringers,  9  in.  X  16  in.  X  32  ft. 
Jack-stringers,  7  in.  X  16  in.  X  32  ft. 
Spreaders,  3  in.  X  12  in. 
Bent:  Cap,  12  in.  X  14  in-  X  16  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in. 
Intermediate  caps  and  sills,  12  in.  X  14  in. 
Sway-bracing  :   Horizontal,  4  in.  X  10  in. 

Diagonal,  4  in.  X  10  in. 
Main  sill,  12  in.  X  14  in. 
Longitudinal  bracing :  Horizontal,  6  in.  X  loin. 

Diagonal,  6  in.  X  10  in. 
Purlins,  12  in.  X  12  in.  X  18  ft. 

Dimensions  of  Iron  Details. 

Bolts :  f  in.  X  5o|-  in. ;  floor-system  to  caps. 

£  in.  X  41  in. ;  sills  to  caps  of  different  decks. 

£  in.  X  37  in. ;  outside  guard-rails  to  jack-stringers. 

|  in.  X  27  in. ;    ) 

\  longitudinal  bracing. 
|  in.  X  24|  in. ;  \ 

£  in.  X  23  in.  ;  sway-brace  splice,  sill-splice,  horizontal  sway-bracing  to  posts. 

£  in.  X  22  in. ;   stringer-joints  ;  packing-bolts. 

£  in.  X  19  in. ;  sway-braces  to  posts. 

f  in.  X  II  in.;  inside  guard  rails  to  ties. 
Drift-bolts  :  f  in,  X  24  in. ;  sill  to  piles. 
Dowels  :  I  in.  X  6  in. ;  posts  to  caps  and  sills. 
Spikes  :  Cut  6o-penny  ;  spreaders  and  brace-blocks  to  caps. 

Boat,  f  in.  X  9  in. ;  sway-braces  to  posts. 
Cast  washers  ;  Under  head  and  nut  of  each  bolt. 


PLATE   XXV.— STANDARD   FRAMED   TRESTLE,   FORT   WORTH    &   DENVER   CITY   RAILWAY 

128 


A    TREATISE  ON    WOODEN    TRESTLE  BRIDGES.  129 


STANDARD  FRAMED  TRESTLE,  FORT  WORTH  &  DENVER  CITY  RAILWAY 

PLATE  XXV. 

Dimensions  of  Timbers. 

Floor-system :    Guard-rails,  5  in.  x  8  in.  X  29  ft. 
Ties,  6  in.  X  8  in.  x  10  ft. 
Stringers,  8  in.  x  14^  in. 
Bent:  Cap,  12  in.  X  12  in.  x  14  ft. 
Plumb-posts,  12  in.  x  12  in. 
Batter-posts,  12  in.  x  12  in. 
Intermediate  cap  and  sill,  12  in.  X  12  in. 
Sway-bracing :  Horizontal,  3  in.  x  8  in. 

Diagonal,  3  in.  x  8  in. 
Main  sill,  12  in.  x  12  in. 


fc^ 


PLATE  XXVI.— DOUBLE-DECK   TRESTLE,    RICHMOND   &    DANVILLE   R. 


130 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  131 


STANDARD  FRAMED  TRESTLE,  RICHMOND  &  DANVILLE  RAILROAD.— PLATE  XXVI. 

Dimensions  of  Timbers. 
Floor-system  :    Guard-rails,  8  in.  X  8  in. 

Ties,  8  in.  X  8  in.  x  10  ft. 
Stringers,  7  in.  x  14  in. 
Spreader,  2  in.  x  4  in.  x  3  ft.  9  in. 
Bent:  Cap,  12  in.  X   12  in.  x  12  ft. 
Plumb-posts,  12  in.  x  12  in. 
Batter-posts,  10  in.  X  12  in. 
Counter-posts,  10  in.  X  12  in. 
Intermediate  sills  and  caps,  12  in.  x  12  in. 
Sway-braces,  3  in.  x  10  in. 
Main  sill,  12  in.  X  12  in. 
Purlins,  10  in.  X  12  in.  X  27  ft. 
Sub-sills,  10  in.  X  12  in. 
Longitudinal  braces,  3  in.  X  10  in. 

Dimensions  of  Iron  Details. 

Bolts  :  X  -    —  ;  guard-rails  to  jack-stringers. 

f  in.  X  -    —  !  stringer-joints  ;  packing-bolts. 

X  36  in. ;  floor-system  to  caps. 

£  in.  X  -    — ;  longitudinal  bracing  to  posts. 
Spikes :  -     -  X  7  in. ;  sway-braces  to  posts,  etc. 

—  ;  spreaders  to  ties. 
Cast  washers :  Under  head  and  nut  of  each  bolt. 


yj 5----.-- 

FIG.  i. — CROSS-SECTION. 


FIG.  2. — ELEVATION. 


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FIG.  3. — PLAN. 

PLATE   XXVII.— STANDARD    FRAMED   TRESTLE,    CLEVELAND    &    CANT'ON    RAILROAD. 

132 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  133 


STANDARD  FRAMED  TRESTLE,  CLEVELAND  &  CANTON  RAILROAD.— PLATE  XXVII. 

Dimensions  of  Timbers. 

Floor-system :  Guard-rails,  8  in.  X  8  in.,  notched  I  in.  over  ties. 

Ties,  7  in.  X  9  in-  X  8  ft.,  notched  i  in.  over  stringers. 
Stringers,  7  in.  X  14  in.  X  15  ft.,  notched  i  in.  over  caps. 
3  in.  X  15  in.  X  20  in. 


Brace-blocks,  , 

'3  in.  X  15  m.  X  34  m. 

Bents:  Caps,  6  in.  X  12  in.  X  12  ft. 

All  posts,  6  in.  X  12  in. 

Sills,  6  in.  X  12  in. 

Sway-braces,  3  in.  X  10  in. 

Tenon-blocks,  3  in.  X  12  in.  X  3  ft. 
Longitudinal  braces:  Girts,  4  in.  X  10  in.  X  17  ft. 

6  in.  X  8  in. 


Diagonals,  , 

j  3  in.  X  8  in. 

Dimensions  of  Iron  Details. 

Bolts:  f  in.  X  18  in.;  post,  sill,  and  cap;  packing-bolts, 
fin.  X  28  in.;  stringer-joints;  packing-bolts, 
f  in.  X  21  in.;  sway-braces  to  posts. 

f  in.  X ;  diagonal  longitudinal  braces  to  pos 

f  in.  X  17  in.;  diagonal  longitudinal  braces  to  posts;  intersection  of  diagonals. 

(  guard-rails  to  ties. 

Lag-screws :  f  in.  X  ,  \ 

( brace-blocks  to  caps. 


SCALE  OF  FEET\ 

^t...9 1  ??  m  7  ?  n° ...'-.  v6  .-rrT2rg 

FIG.  i. — CROSS-SECTION. 
PLATE   XXVIII,— STANDARD   TRESTLE,    CALIFORNIA   CENTRAL   RAILWAY. 


134 


^-f3Hft-l^7g»-Cp-PT-FM 


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n-en-m-tvt-eo-ea-rt*, 


£^F£ 


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; 15'- 


FIG.  3. — CAP  AND  POST  JOINT. 


FIG.  4. — POST-SPLICE. 


— <3Va"  >S*S y^" 


iiu.i.iiL?' 


SCALE  OF  FEET 

y  .*    t L 


FIG. '2.  -ELEVATION.  FIG.  6. — SILL  AND  POST  JOINT  DETAILS. 

PLATE   XXIX.— STANDARD   TRESTLE,    CALIFORNIA   CENTRAL   RAILWAY. 


135 


136  A    TREATISE  ON    WOODEN   TRESTLE  3XIDGES. 


STANDARD  FRAMED  TRESTLE,  CALIFORNIA  CENTRAL  RAILWAY. 
PLATES  XXVIII  AND  XXIX. 

Dimensions  of  Timbers. 

Floor-system :  Guard-rails,  6  in.  X  8  in.,  notched. 
Ties,  6  in.  X  8  in.  X  9  ft,  notched. 
Stringers,  8  in.  X  16  in.  x  30  ft. 
Bents:  Caps,  6  in.  X  12  in.  X  14  ft. 
All  posts,  6  in.  X  12  in. 
Intermediate  caps,  6  in.  X  12  in. 
Diagonal  sway-braces,  3  in.  x  12  in. 
Sill,  6  in.  X  14  in. 
Under  part  of  sill,  8  in.  X  18  in. 
Pile-caps,  12  in.  x  12  in.  x  6  ft. 
Packing-blocks  between  posts  and  cap-pieces,  6  in.  x  12  in.  x  42  in.,  and  6  in.  x 

12  in.  x  2  ft.  9  in. 
Longitudinal  braces,  5  in.  X  10  in.  x  32  ft. 

Dimensions  of  Iron  Details. 
Bolts:  Guard-rails  to  stringers. 

Stringer-joints ;  packing-bolts. 

•f  in.  X  21  in. ;  sway-braces  to  posts. 

•f  in.  X  9  in. ;  intersection  of  sway-braces. 

f  in.  X  21  in. ;  intermediate  caps  to  posts;  girts  to  posts. 

f  in.  X  25  in. ;  two  parts  of  sill  together;  brace-pile  to  pile-caps. 
Drift-bolts  :  f  in.  X  20  in.  sill  to  pile-caps  ;  caps  to  piles. 
Cast  washers:  Under  head  and  nut  of  each  bolt. 

Cast  separators  or  spools :  3  in.  x and  6  in.  x . 

Cast  strap  :  20  in.  X  3  in.  X  I  in.  as  per  detail ;  girts  to.  posts. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES. 


Floor-system 


Bent 


PLATE   XXX.—  STANDARD   FRAMED  TRESTLE,    TOLEDO,   ST.   LOUIS  &   KANSAS  CITY   RAILROAD. 

STANDARD  FRAMED  TRESTLE,  TOLEDO,  ST.  Louis  &  KANSAS  CITY  RAILROAD. 

PLATE  XXX. 

Dimensions  of  Timbers, 
Guard-rails,  6  in.  X  6  in.  x  18  ft. 
Ties,  6  in.  x  8  in.  x  9  ft. 
Stringers,  7  in.  X  18  in.  X  18  ft. 
Spreader,  3  in.  x  12  in.  x  3  ft. 
Brace-blocks,  3  in.  X   12  in.  X  15  in. 
Cap,  7  in.  X  14  in.  X  14  ft. 
Plumb-post,  6  in.  x   10  in. 
Inclined  posts,  6  in,  x  10  in. 
Splice-blocks,  6  in.  x  10  in.  x  2  ft. 
Sway-bracing  :  Horizontal,  6  in.  x  10  in. 

Diagonal,  3  in.  x  10  in. 

Sill,  6  in.  x  10  in.,  9  in.  X   18  in.,  and  7  in.  x  18  in. 
Longitudinal  bracing  :   Horizontal,  6  in.  x  10  in.  X  18  ft. 
Diagonal,  6  in.  X  10  in. 

Dimensions  of  Iron  Details. 
stringer-joints;  packing-bolts. 
cap-pieces  together. 
post-splices,  sway-brace  intersections,  posts  to  tenon-blocks,  posts 


Bolts:  f  in.  X  31  in. 
|  in.  x  23  in. 


§  in.  x  21  in. 

to  sill. 
Lag-screws:  |  in.  x  9  in.;  sway-braces  to  posts,  longitudinal  braces  to  posts,  etc.;  spreader 

and  brace  blocks  to  cap. 
I  in.  x  14  in.  ;  sill-pieces  together. 
Drift-bolts:  f  in.  x  I  in.  X  20  in. ;  sill  to  piles. 
Cast-separators  :  4  in.  thick  )  , 

f  f°r  s-m-  bolts. 
2  m-  ) 

Cast-washers :  Under  head  and  nut  of  each  bolt. 
Splice-plates:  T5B-  in.  X  2  in.  X  13  in.;   stringer-joints. 


Sheet-iron  :  No.  27,  30  in.  X  36  ft 
No   27,  24  in.  x  14  ft. 

No.  27, x  34  ft. 

Also,  sheet-iron  to  cover  all  places  where  fire  can  lodge. 


covering  stringers, 
covering  caps, 
covering  sill. 


A  B 

FIG.  r.— FRAMED  BENTS.  FIG.  2.— 40  TO  90  FT.  HIGH. 

PLATE   XXXI.— STANDARD    FRAMED    TRESTLES,  ATLANTIC   &    PACIFIC    RAILROAD. 

138 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  139 


STANDARD  FRAMED  TRESTLE,  ATLANTIC  &  PACIFIC  RAILRC  A.D.— PLATE  XXXI. 

(See  also  Plate  III.) 

» 

Dimensions  of  Timbers. 

Floor-system  :  See  Plate  III. 

Bent — Fig.  I  :  Cap,  12  in.  X  14  in.  X  14  ft. 

Plumb-posts,  12  in.  X  12  in. 

Batter-posts,  12  in.  x  12  in. 

Sway-braces,  3  in.  x  10  in. 

Sill,  12  in.  X  12  in. 
Fig.  2  :  Cap,  12  in.  x  14  in. 

Plumb-posts,  6  in.  X  12  in. 

Batter-posts,  6  in.  X  12  in. 

Intermediate  caps,  6  in.  X  12  in. 

Sway-braces,  3  in.  x  10  in. 

Sill,  8  in.  x  12  in.,  and  12  in.  x  12  in. 
Sub-sills,  12  in.  x  12  in. 
Pile-caps,  12  in.  X   14  in. 

Dimensions  of  Iron  Details. 
See  Plate  III. 


FIG.  i. — DOUBLE  AND  TRIPLE  DECK  FRAMED  TRESTLE. 


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FIG.  2. — FLOOR-SYSTEMS  OK  TRESTLE-BRIDGES. 


PLATE  XXXII.— STANDARD   FRAMED   TRESTLE,    MILWAUKEE  &    NORTHERN    RAILROAD. 

140 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  141 


STANDARD  FRAMED  TRESTLE,  MILWAUKEE  &  NORTHERN  RAILROAD.— PLATE  XXXII. 

Dimensions  of  Timbers. 
Floor-systems — A:  Ties,  6  in.  X  8  in.  X  12  ft. 

Track-stringers,  7  in.  X.i6  in.  X  30  ft. 
Jack-stringers,  6  in.  or  7  in.  X  16  in.  x  15  ft. 
B:  Ties,  6  in.  X  8  in.  X  12  ft. 

Track-stringers,  12  in.  X  15  in.  X  i  5  ft. 
Jack  stringers,  7  in.  X  15  in.  X  15  ft. 
Track-stringer  corbels,  10  in.  X  12  in.  X  6  ft. 
Jack-stringer  corbels,  7  in.  X   10  in.  X  6  ft. 
C :  Ties,  6  in.  X  8  in.  x  12  ft. 

Track-stringers,  7  in.  X  14  in.  X  16  ft. 
Jack-stringers,  7  in.  X  14  in.  X  15  ft. 
K.,  G.  B.  &  W.  R.  R.  : 

Ties,  6  in.  X  8  in.  X  12  ft. 
Track-stringers,  7  in.  X  14  in.  X  16  ft. 
Jack-stringers,  7  in.  X  14  in.  x  16  ft. 
Bent:  Cap,  12  in.  X  12  in.  X  14  ft. 

Plumb-posts,  12  in.  X  12  in.,  and  7  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in.,  and  7  in.  X  12  in. 
Intermediate  caps  and  sills,  3  in.  X  12  in. 
Sway-braces,  3  in.  X  12  in. 
Main  sill,  7  in.  x  12  in. 
Packing-blocks,  3  in.  X  12  in.  x  3  ft. 
Pile-caps  :   12  in.  X  12  in.  X  4  ft. 
Longitudinal  braces  :  3  in.  X  12  in.  X  16  ft. 

Dimensions  of  Iron  Details. 
Bolts :  f  in.  X  19^  in. 

f  in.  X  22^  in. 

|  in.  X  29^  in. 
Spikes  :  X . 


10  IS  ?0  25  BO  S,S  40 


FIG.  i. 


FIG.  2. — ELEVATION. 


PLATE   XXXIII.— FRAMED    TRESTLE,    ST.  PAUL,   MINNEAPOLIS   &   MANITOBA    RAILROAD. 

142 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  143 


FRAMED  TRESTLES,  ST.  PAUL,  MINNEAPOLIS  &  MANITOBA  RAILROAD. 
PLATES  XXXIII  AND  XXXIV. 

Dimensions  of  Timbers. 

FIGS.   I  AND  2. 

Floor-system:  Ties,  6  in.  X  8  in.  X   12  ft. 

Track-stringers,  7  in.  X  14  in.  X  20  ft. 
Jack-stringers,  7  in.  X  14  in.  X  20  ft. 
Floor-beams,  12  in.  X  12  in.  X  14  ft. 
Sub-stringers,  12  in.  X  12  in.  X  30  ft. 
Corbels,  12  in.  X  12  in.  X  5  ft. 
Bent :  Cap,  6  in.  X  10  in.  X  14  ft. 
Posts,  10  in.  X  12  in. 
Sway-bracing  :  Horizontal,  8  in.  X  8  in. 
Diagonal,  3  in.  X  10  in. 
Splice-blocks,  6  in.  X  12  in.  X  6  ft. 
Sill,  10  in.  X  12  in. 
Pile-caps,  12  in.  X  14  in. 

Knee-braces  :  Top  cord,  10  in.  X  10  in.  X  10  ft. 
Diagonals,  10  in.  X   10  in.  X   18  ft. 

Longitudinal  braces :  Horizontal,  8  in.  X  8  in.  X  34  ft 
Brackets,  3  in.  X  8  in.  X  14  ft. 


SCALE  OF  FEET 


FIG.  3.  —  CROSS-SECTION.  FIG.  4.  —  ELEVATION. 

PLATE   XXXIV.—  FRAMED    TRESTLE,    ST.    PAUL,    MINNEAPOLIS   &    MANITOBA    RAILROAD. 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  145 

FIGS.    3    AND  4, 
Floor-system :  Guard-rails,  5  in.  X  8  in. 

Ties,  6  in.  X  8  in.  X  12  ft. 
Track-stringers,  7  in.  X  14  in.  X  20  ft. 
Jack-stringers,  7  in.  X   14  in.  X  20  ft. 
Floor-beams,  12  in.  X  12  in.  X  14  ft. 
Sub-stringers,  10  in.  X   12  in.  X  30  ft. 
Bent:  Upper  cap,  10  in.  X  12  in.  X  14  ft. 
Lower  cap,  10  in.  X  14  in.  X  20  ft. 
Upper  posts,  10  in.  X  10  in. 
Main  posts,  10  in.  X   12  in. 
Sway-bracing :  Horizontal,  8  in.  X  8  in. 
Diagonal,  3  in.  X  10  in. 
.    Splice-blocks,  6  in.  X   12  in.  X  6  ft. 
Sill,  10  in.  X   12  in. 

Sway-brace  splice-block,  6  in.  X  8  in.  X  5  ft. 
Sill  splice-block,  6  in.  X   12  in.  X  4  ft. 
Pile-caps,  12  in.  X   14  in.  X  4  ft.  6  in. 
Longitudinal  bracing  :  Horizontal,  6  in.  X  10  in.  X  34  ft. 

Brackets,  3  in.  X  8  in. 

Floor  trusses:  Upper  chord,  10  in.  X  10  in.  X  12  ft. 
Lower  chord,  10  in.  X  12  in.  X  30  ft. 
End-posts,  10  in.  X   10  in.  X  12  ft. 
Diagonals,  5  in.  X  8  in.  X  14  ft. 
Lateral  braces,  6  in.  X  /  in.  X  14  ft. 
Foot-blocks  :  Corbels,  10  in.  X  14  in.  X  8  ft. 

Dimensions  of  Iron  Details. 
Bolts  :  f  in.  X  I2|-  in. ;  guard-rails  to  ties. 

fin.  X  17^  in. ;  stringer-joints;  packing-bolts. 
f  in.  X  27^  in. ;  longitudinal  braces  to  posts. 
-|  in.  X  28^  in. ;  post-joints, 
f  in.  X  31^  in.  ;  diagonal  sway-braces  to  posts. 
|  in.  X  4i£  in. ;  horizontal  sway-braces  to  posts. 

Drift-bolts:  fin.  X  20  in.;  stringers  to  floor-beams;  floor-beams  to  sub-stringers;  sub- 
stringers  to  caps  ;  main  sill  to  pile-caps  ;  pile-caps  to  piles. 
Spikes  :  Boat,  \  in.  X   10  in. ;  ties  to  stringers. 

f  in.  x  7  in.;  sway-bracing  to  posts;  bracket-braces  to  posts;  and  longi- 
tudinal bracing. 
Iron  in  trusses :  Rods,  \\  in.  X  11  ft.  4  in. ;  between  upper  and  lower  chords. 

Tie-rods,  -     -  x  -     —  ;  three  trusses  together. 
Bolts :  -      -  X ;  intersection  of  panel  diagonals. 

-  X  2  ft.  1 1  in. ;  end-posts  to  lower  chords. 

-  x  3  ft.  5^  in. ;  lower  chords  and  corbels  to  caps. 


—  i 

^    —-—J6'3' 


VaxJ? 


FIG.  3. — STRINGER  JOINT. 
FIG.  i. — ELEVATION. 


SCALE  OF  FEET 


FIG.  2. — CROSS-SECTION. 


PLATE  XXXV.— DOUBLE-TRACK  FRAMED  TRESTLE,  NEW  YORK,  WOODHAVEN  &  ROCKAWAY  RAILROAD. 

146 


A    TREATISE  ON    WOODEN   TRESTLE  BRIDGES.  147 


DOUBLE-TRACK  FRAMED  TRESTLE,  NEW  YORK,  WOODHAVEN  &  ROCKAWAY  RAILROAD. 

PLATE  XXXV. 

Dimensions  of  Timbers. 

Floor-system  :  Guard-rails,  8  in.  X  6  in. 

Ties,  6  in.  X  8  in.  X  21  ft. 

Stringers,  5  in.  X  14  in.  X  32  ft.  6  in. 

Corbels,  5  in.  X  8  in.  x  5  ft.  9  in. 
Beait:  Cap,  12  in.  X   12  in.  X  24  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  x  12  in. 
Sway-braces,  3  in.  x  10  in. 
Sill,  12  in.  x   12  in. 
Sub-sills, 

Dimensions  ef  Iron  Details. 

Bolts:  f  in.  X  13  in.  ;  guard-rails  to  ties. 

f  in.  X in.  ;  stringer-joints  ;  packing-bolts. 

f  in.  X  -     -  in. ;  stringers  to  corbels. 

|  in.  X  ;  ) 

\    stringers  to  caps, 
i  in.  X  ;  f 

Plates:  £  in.  X  3  in.  X  17  in. ;  corbel-bolts. 

Spikes  :  Ties  to  stringers. 

Cast-washers  :   i  in.  x  3  in. ;  under  head  and  nut  of  each  bolt. 


iSiiEElip:  ^jiSSSJ^^^^i 

EHr   ZJt^SHSE!:: 


FIG.  i.~ SECTIONAL  AND  SIDE  ELEVATIONS,  WINTHROP'S  COVE  TRESTLE. 

'soaarocomefatkreen  Jfiefiea 


FIG.  2.-LONG1TODINAL  AND    TRANSVERSE  SECTIONS  OF    24   FT.    B.«,    WlNTHROrt   COVE   TRESTLE. 

^ 


Fio.'J— SECTIONAL  AND  SIDE  ELEVATIONS,  THAMES  RIVEK  BRIDGE  APPROACH  TRBSTLE. 
PLATE   XXXVI  --TRESTLE    PLANS,    NEW    YORK,    PROVIDENCE    &    BOSTON    RAILROAD 


A    TREATISE   ON    WOODEN    TRESTLE  B RIDGES.  14. 

FRAMED  TRESTLES,  NEW  YORK,  PROVIDENCE  &  BOSTON  RAILROAD.— 

PLATE  XXXVI. 

FIGS.  I    AND   2:    WINTHROP'S   COVE   TRESTLE,    ON   8°    15'   CURVE   AND   0.714   GRADE. 
FIG.  3  :   THAMES  RIVER  BRIDGE  APPROACH. 

Dimensions  of  Timbers, 
Floor-system  :    Guard-rails,  8  in.  X  8  in. 

Ties,  8  in.  X  1 1  in.  X  22  ft. 
Stringers,  8  in.  X  14  in.  X  24  ft. 

\   2  in.  x   14  in-  X  4  ft. 
Splice-blocks, !  4  in>  x  ,4  in.  x  6  ft. 

Bent:  Cap,  12  in.  X  H'in.  X  23  ft. 
Plumb-posts,  12  in.  X  12  in. 
Batter-posts,  12  in.  X  12  in. 
Sway-braces,  4  in.  X  12  in. 
Sill,  12  in.  X  14  in. 

Longitudinal  braces,  4  in.  X  1 2  in.  X  25  ft. 
Purlins,  12  in.  X   14  in. 
Purlin  splice-blocks,  4  in.  X   14  in.  X  6  ft. 
Foundation:   Pile-cap,  12  in.  X   14  in. 
Piles,  12  in.  diameter. 
Brace-piles,  12  in.  diameter. 
Knee-braces:   Upper  chord,  10  in.  X   10  in.  X  5  ft. 

Straining-beams,  10  in.  X  10  in.  X  21  ft. 
Diagonals,  6  in.  X   14  in. 
Splice-block,  12  in.  X  14  in.  X  4  ft. 

Dimensions  of  Iron  Details. 
Bolts:  f  in.  X  15!  in.  ;  ) 

f  in.  X  I9iin.;fguard-railstoties- 

f  in.  X  i8|  in.  sway-braces  to  posts,  etc. 

|  in.  X  22  in.  ;  purlin  splice. 

f  in.  X  26|  in. ;  upper  chord  to  stringers. 

f  in.  X  16  in. ;  foot  of  knee-brace  to  prevent  splitting. 

-|  in.  X  27^  in. ;  knee-braces  to  purlins,  to  packing-blocks,  to  posts. 

i  in.  X  18  in.  ;  longitudinal  braces  to  posts. 

i  in.  x  22J-  in. ;  )  stringer;ojnts .  packing-bolts, 
i  in.  x  20|-  in. ;  ) 

i£  in.  X  34  in.  ;  batter  and  sway-brace  piles  to  piles. 
Drift-bolts:  f  in.  x  f  in.  x  21  in.;  stringers  to  caps, 
i  in.  X  18  in. ;  sills  to  posts, 
i  in.  X  20  in.  ;  cap  to  posts ;  pile-cap  to  piles. 

Spikes :  X  ;  ties  to  stringers. 

f  in.  X  12  in. ;  purlins  to  pile-caps, 
f  in.  X  16  in. ;  sills  to  purlins. 
Washers,  wrought  :  f-in.  bolts ;  guard-rail  bolts. 

4  in.  X  4  in.  X  f  in. ;  sway-brace  bolts. 
4  in.  X  4  in.  X  \  in. ;  longitudinal  brace-bolts. 
^,  4  in.  X  4  in.  X  f  in.  ;  sway-brace,  pile,  etc.,  bolts. 
3  in.  x  f  in. ;  purlin  splice-bolts. 
3^  in.  X  •£  in. ;  stringer-bolts. 
Cast  separators :  3^  in.  X   i  in. ;  between  splice-blocks  and  stringers. 

3!  in.  x  4  in. ;  between  stringers,  where  there  are  no  splice-blocks. 


f,  -t 

'ft — • 


Ir 


-a 


V>e>wfC"0 

Longitudinal  Section  through  A  B. 
Post  Spices  not  sho«tn  frainedthrouqhoitf,  to  break  joints. 


sopi  «r.==  _j^..nia;^ca.ji.j 
Section  through  CD,mtli  Erection  Gear.  Stone  Ballast on  r,rib  nor  sfio*n 


«;_..«...« 

PLATE   XXXVII.— DEEP-WATER    FRAMED    TRESTLE,    INTERCOLONIAL    RAILWAY. 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  151 


DEEP-WATER  FRAMED  TRESTLE,  INTERCOLONIAL  RAILWAY. — PLATE  XXXVII. 

As  the  structure  illustrated  in  Plate  XXXVII  is  exceptional,  and  had  to  fulfil  unusual 
requirements,  it  was  thought'best  to  reprint  the  full  description  of  the  work,  as  given  in  the 
Railroad  Gazette  of  April  9,  1886. 

It  was  designed  to  carry  a  short  branch-line  of  minor  importance  across  a  narrow  strait  (the  Narrows) 
in  Halifax  Harbor.  The  water  being  from  65  to  80  feet  deep,  some  peculiar  features  of  design  and  methods 
of  construction  were  naturally  required. 

The  branch  as  constructed  (the  Dartmouth  Branch)  is  about  5  miles  long.  To  avoid  the  trestle  it 
would  have  been  necessary  to  begin  the  branch  at  a  point  9  miles  or  at  one  14  miles  distant,  which  would 
have  made  it  seven  or  12  miles  long,  and  required  a  special  train  service  in  operating  it. 

Richmond  yard  being  on  the  shore  of  the  narrow  passage  between  Halifax  Harbor  and  Bedford  Basin, 
at  the  most  favorable  point  for  bridging  it,  the  structure  shown  was  built  instead,  permitting  the  branch  to 
leave  the  yard  inside  the  semaphore,  thus  enabling  the  shunting-engines  to  do  the  business  on  it  without 
in  any  way  interfering  with  the  traffic  of  the  main  line. 

The  Narro'ws  are  about  1500  ft.  wide,  and  from  65  to  80  ft.  deep  in  the  channel  where  the  line  crosses 
for  a  distance  of  650  ft.  The  mean  rise  and  fall  of  the  tide  is  6  ft.,  causing  a  current  through  the  Narrows 
of  about  \\  miles  an  hour.  At  spring-tide,  with  a  strong  wind,  this  is  sometimes  increased  to  three  miles 
an  hour. 

The  bottom  is  generally  compact  gravel,  mixed  with  stones  and  bowlders.  In  no  place  could  a  bar  be 
driven  more  than  3  ft. ;  below  that  depth  was  apparently  ledge-rock. 

In  severe  winters  ice  forms  in  Bedford  Basin,  but  owing  to  the  extreme  narrowness  of  the  outlet  into 
the  harbor,  it  is  held  in  the  basin  until  decayed  by  the  spring  weather.  The  bridge  has  a  total  length  of 
2050  ft.,  of  which  1204  ft.  is  on  piling,  650  ft.  trestling  in  the  channel,  and  the  remaining  196  ft.  is  a  steel 
swing-bridge. 

The  piling,  where  in  deep  water,  was  well  stiffened  transversely  by  brace-piles,  which  were  driven  plumb 
and  afterwards  drawn  over  to  a  considerable  angle,  when  they  were  fitted  to  the  capping  and  bolted.  The 
pivot  pier  for  the  swing-bridge  is  of  masonry,  and  has  a  passage  for  vessels  on  each  side  of  85  ft.  in  the  clear- 

From  the  top  of  the  pier  to  2  ft.  below  low-water  it  is  laid  in  cement,  and  is  circular  in  form,  with  a 
diameter  of  20  ft.  Thence  to  the  bottom,  about  33  ft.,  it  is  built  square,  with  a  batter  of  i  in  12,  and  is  laid 
without  mortar.  Large  stones  only  were  permitted  to  be  used  in  the  square  portion  of  the  work,  and  were 
required  to  be  full  bedded  throughout  and  closely  fittel.  Each  course  was  carefully  dressed  and  put 
together  in  the  quarry  upon  a  level  platform ;  the  stones  were  then  marked  with  white  paint  at  all  connec- 
tions with  their  fellows,  and  carefully  numbered. 

The  courses  were  then  forwarded  to  the  site  of  the  pier,  where  they  were  lowered  from  a  lighter,  each 
stone  in  its  proper  order,  and  received  by  a  diver,  who,  standing  on  the  course  last  laid,  placed  them  in 
position,  using  lines,  straight-edge,  and  spirit-level  to  insure  all  possible  accuracy.  A  complete  course  was 
frequently  laid  in  a  day  by  the  one  diver  employed,  for  with  the  footings  once  properly  levelled  he  had  but 
little  to  do  to  keep  the  work  in  good  order.  Before  putting  in  the  foundation  courses  the  sloping  bottom 
was  properly  benched  by  the  diver,  and  frequent  testings  as  the  work  proceeded  showed  that  perfect  line  and 
level  was  being  kept. 

No  accident  or  difficulty  of  any  kind  occurred  in  the  construction  of  the  pier,  the  work  being  carried  on 
as  smoothly  and  regularly  as  if  in  the  open  air;  the  steam  winch  of  the  lighter  working  with  quickness  and 
precision  as  the  diver  signalled  his  directions. 

The  time  occupied  in  building  the  pier  was  70  days,  the  same  diver  being  employed  throughout.  The 
cost  per  cubic  yard  was  $23. 

The  trestling  across  the  channel  consisted  of  timber  bents,  framed  as  shown  on  the  accompanying  draw- 
ings. The  bents  were  placed  25  ft.  apart  between  centres,  and  rested  on  a  ballasted  timber  crib,  which  had 
previously  been  lowered  in  place.  The  bents  were  floated  to  the  site  and  drawn  down  to  their  seat  on  the 
cribs  by  the  methods  shown  in  the  cuts  and  described  hereafter.  The  work  of  putting  down  the  trestling  was 
commenced  on  the  west  side  of  the  channel  August  8,  1884,  and  on  the  east  side  October  4,  1884.  In  all 
25  bents  were  put  down,  in  depths  generally  from  70  to  80  ft.  The  two  sides  were  connected  November  20, 


i52  A    TREATISE   QN    WOODEN   TRESTLE  BRIDGES. 

1884.  When  the  level  portion  of  the  channel  was  reached  three  bents  were  sometimes  put  down  in  a  week. 
One  diver,  with  occasionally  an  assistant,  worked  on  each  side  of  the  channel.  In  addition  to  the  travelling 
derrick  shown,  a  lighter  was  provided  for  each  side,  having  a  steam-winch  for  lowering  ballast,  etc.,  and  a 
steam-pump  for  the  diver. 

The  correct  centring  at  each  bent  was  given  by  a  theodolite  placed  at  the  outer  end  of  the  piling,  and 
at  slack-water  lining  in  the  rope  holding  the  hammer  of  the  floating  pile-driver,  which  had  been  brought 
approximately  into  position,  with  the  hammer  raised  about  one  foot  from  the  bottom.  When  correctly 
lined  the  diver  was  signalled,  and  a  bolt  driven  into  the  ground  at  the  centre  of  the  hammer. 

It  is  not  anticipated  that  there  will  be  any  trouble  from  worms,  as  the  strength  of  the  current  and  the 
large  amount  of  fresh  water  discharged  into  the  basin  render  their  presence  in  the  Narrows  improbable. 
The  wharves  in  the  harbor  also  show  that  the  nearer  the  Narrows  are  approached  the  less  destructive  are 
the  worms.  It  is  therefore  hoped  that  the  bents  below  low-water  will  but  rarely  require  to  be  renewed,  and 
they  have  been  constructed  of  sawn  hemlock,  a  cheap  and  sufficiently  good  material  where  secure  from 
decay.  The  upper  or  supplementary  bents  were  constructed  of  white  pine,  as  more  durable,  and  are  so  con- 
nected with  the  lower  bents  that,  though  erected  as  a  whole,  they  can  be  easily  separated  and  renewed. 

The  work  of  preparing  the  bottom  for  the  crib  foundation  of  the  bent  was  as  follows  :  Six  flattened  tim- 
bers 10  ft.  long  and  weighted  were  lowered  to  the  bottom.  These  were  bedded  by  the  diver,  and  were 
brought  to  a  uniform  level  by  means  of  a  long  straight-edge  with  spirit-level  attached.  Where  the  slope  or 
character  of  the  ground  demanded,  additional  timbers  were  placed  under  these  bed  logs  to  bring  them  to 
the  required  height,  the  whole  being  filled  in  and  about  with  stone.  In  fairly  level  ground  the  six  logs 
could  be  bedded  by  one  diver  in  \\  days.  In  the  worst  cases,  where  the  slope  of  the  bottom  was  i  in  2£ 
longitudinally  and  i  in  5  transversely,  it  took  the  same  diver  six  days  to  bed  them  properly. 

The  crib  for  each  boat  was  next  launched  from  the  ways  on  which  it  was  constructed,  and  floated  out, 
and  the  lines  from  the  winch  on  the  travelling  derrick  attached  to  the  chain  at  each  end,  by  hooking  on  the 
iron  swivel-blocks  as  shown. 

The  crib  was  supported  until  about  nine. tons  of  ballast  had  been  thrown  on,  when  it  was  lowered  to  its 
place  on  the  bed-logs.  When  near  the  bottom  the  diver  signalled  any  slight  alteration  required  in  its  posi- 
tion, and  the  correction  was  made  by  side  lines.  The  time  occupied  in  lowering  the  cribs  and  finally  adjust- 
them  was  about  i£  hours. 

In  difficult  bottom  the  diver  then  proceeded  to  the  next  foundation,  leaving  an  assistant  to  place  the 
remainder  of  the  ballast  on  the  crib.  This  took  about  if  days  to  do  properly. 

The  bent,  which,  like  the  crib,  was  built  on  ways  on  the  shore,  was  next  launched  and  towed  to  the 
site,  and  the  lines  from  the  travelling  derrick,  which  passed  through  the  blocks  at  the  ends  of  the  crib,  were 
attached  to  the  sill  of  the  bent.  About  10  tons  of  ballast  were  next  placed  in  the  lockers  near  the  bottom, 
and  the  engine  was  started,  drawing  the  bent  gradually  downward  till,  led  by  the  blocks,  it  rested  in  its 
proper  place  on  the  crib.  It  was  readily  adjusted  vertical  by  a  line  to  the  cap,  and  was  then  secured  by 
bolting  on  temporary  stays  from  the  end  of  the  bridge.  The  diver  then  permanently  secured  the  bent  to 
the  crib  in  the  manner  shown,  by  lifting  the  galvanized-iron  fastenings  into  place,  fitting  on  the  cover-blocks 
and  screwing  home  the  nuts.  The  fastenings  were  so  arranged  that  they  could  be  thrown  back  out  of  the 
way  until  the  bent  was  finally  settled  in  place. 

The  time  occupied  in  towing  out,  hauling  down,  and  adjusting  a  bent,  together  with  the  complete  fitting 
and  securing  of  the  fastenings,  was  in  general  about  \\  days;  of  this  the  actual  hauling  down  occupied  but  a 
small  portion. 

The  permanent  stringers  were  next  placed  and  sleepered,  the  rails  for  the  derricks  laid,  and  the  derrick 
run  out  for  the  next  crib. 

The  average  cost  of  the  trestling  per  bent  completed  ready  for  the  rails  was  as  follows : 

n  M.  ft.  B.  M.,  hemlock @  $6.47  $7*-i7 

9  M.  ft.  B.  M.,  pine @  16.00  144.00 

12  knees,       @  3.50  42.00 

500  Ibs.  ordinary  iron @  .04?,  22.50 

1800  Ibs.  galvanized  iron, @  .08  144.00 

Crib — material  and  work @  60.00  60.00 

Framing,  20  M.  ft.  B.  M., @  10  oo  200.00 

Stone  ballast,  66  tons @  .40  26.40 

Diving  work, @  108.00  108.00 

Incidentals, 31-93 

Total,  .      $850.00 


A    TREATISE   ON    WOODEN    TRESTLE  BRIDGES.  153 

The  bents  number  25,  making  the  total  cost  of  the  trestling  $21,250,  or  at  the  rate  of  nearly  $33  per 
lineal  foot. 

No  accident  of  any  kind  occurred  in  putting  down  the  trestle-bents  or  foundations,  everything  working 
smoothly  throughout.  All  iron  to  be  exposed  to  the  action  of  salt  water  was  galvanized.  The  crib  founda- 
tions, from  their  position,  and  from  being  covered  with  stone,  may  be  considered  secure  from  the  action  of 
worms  or  other  destroying  agencies.  Should  a  bent  at  any  time  require  to  be  removed,  it  can  be  easily 
released  from  the  crib  and  a  new  one  substituted.  In  the  deepest  water  the  divers  worked  skilfully  and 
without  difficulty,  and  by  coining  to  the  surface  for  a  few  minutes  every  \\  hours,  were  enabled  to  do  good 
work  throughout  the  entire  day.  All  levelling  and  lining  under  water  was  accurately  done,  as  proved  when 
the  bents  were  drawn  down  to  their  place.  The  divers  were  paid  $150  per  month  each,  with  board;  the 
assistant-divers  about  half  that  amount. 

Steam-pumps  were  used  for  supplying  air,  in  preference  to  those  worked  by  hand,  the  increased  regu- 
larity of  stroke  being  of  importance  in  deep  water.' 

The  current  at  the  bottom,  while  not  so  rapid  as  at  the  surface,  was  more  changeable,  sometimes  almost 
entirely  ceasing  and  then  suddenly  recommencing,  as  though  restrained  temporarily  by  eddies  or  cross-cur- 
rents. The  divers,  however,  were  rarely  prevented  by  the  current  from  working  satisfactorily.  Very  severe 
gales  occurred  during  the  construction  of  the  bridge  and  after  its  completion.  No  movement  or  working 
was  at  all  perceptible  during  their  continuance. 

The  bridge  has  now  been  completed  and  in  operation  nearly  a  year.  Trains  preceded  by  two  locomo- 
tives crossing  at  15  miles  an  hour  have  failed  to  produce  the  slightest  motion  or  settlement  in  any  part  of 
the  structure. 

The  work  was  planned  and  carried  through  under  the  direction  of  Mr.  P.  S.  Archibald,  Chief  Engineer 
of  the  Intercolonial  Railway. 


r-i  n   n  n  n  -r.i 


PLATE   XXXVIII.— STANDARD    FRAMED   TRESTLE,    ESQUIMALT   &    NANAIMO    RAILWAY. 

154 


A    TREATISE  ON    WOODEN    TRESTLE   BRIDGES.  155 


STANDARD  FRAMED  TRESTLE,  ESQUIMALT  AND  NANAIMO  RAILWAY. — PLATE  XXXVIII. 

Dimensions  of  Timbers, 

Floor-system :  Guard-rails,  6  in.  X  9  in. 
Ties,  8  in.  X  9  in.  X  13  ft. 
Stringers,  9  in.  X  16  in. 
Bents:  Caps,  12  in.  X  12  in.  X  16  ft. 

Plumb-posts,  12  in.  x  12  in.,  and  12  in.  X  14  in. 
Batter-posts,  12  in.  X  12  in.,  and  12  in.  X  14  in. 
Counter-posts,  12  in.  X  12  in.,  and  12  in.  x  14  in. 
Sill,  12  in.  x  14  in. 

Intermediate  caps  and  sills,  12  in.  x  12  in.,  and  12  in.  X  14  in. 
Sway-braces,  4  in.  x  10  in. 
Longitudinal  braces,  6  in.  x  8  in. 
Purlins,  6  in.  x  12  in. 
Sub-sills,  12  in.  round,  flatted. 

The  trestle  illustrated  is  built  on  a  10°  curve.  Mr.  Joseph  Hunter  is  the  Chief  Engineer 
of  the  road.  For  further  description,  see  Railroad  Gazette,  February  6,  1891,  p.  89.  In  the 
reduction  of  the  drawing  of  this  trestle  the  figures  become  so  small  that  the  reader  is  referred 
to  the  enlarged  details  for  the  dimensions  which  are  also  "iven  above. 


INDEX. 


Acceptance,  65 

Accounts,  force,  67 

Adze,  59 

Alabama  Great  Southern  R.  R.(  61 

Annual  cost,  2 

Atlantic  &  Pacific  R.  R.,  61,  90 

Augers,  59 

Axe,  59 

Axe,  broad,  59 

Bank  bent,  52 

sill,  52 

Batter  piles,  7 
"       posts,  28 
"  "    ,  length,  28 

"          "    ,  template,  29 
Bay,  refuge,  54 
Bent,  bank,  52 

"    ,  framed,  24 

"    ,  height,  30 

"    ,  pile,  6 
Bents,  spacing,  30 
Blocks,  packing,  32 
Board  measure,  71 
Boat-spikes,  45,  46 
Bolts,  48,  49 

"     ,  button-head,  49 

"     ,  countersunk,  49 

"     ,  drift,  46 

"     ,  weight,  49 
Boring-machine,  58 
Boston  &  Albany  R.  R.,  40,  100 
Bracing,  latticed,  40 

,  longitudinal,  39 
"       ,  sway,  39 

Brantford,  Waterloo  &  Lake  Erie  R.  R.,  61 
Bridge  foremen,  83 

"       numbers,  83 
Bridges,  amount,  I 
"      ,  distribution,  2 
"      ,  iron,  4 
Broad  axe,  59 

Burlington,  Cedar  Rapids  &  Northern  R.  R.,  33.  82 
Burlington  &  Missouri  River  R.  R.,  7,  33 
Button-head  bolts,  49 
California  Central  Ry.,  134-136 
Cant-hook,  60 
Capitalized  values,  2,  3 


Caps,  29 

"    ,  pile,  12 

"    ,  split,  1 2,  30 
Car  pile-driver,  15-19 
Cast-iron,  65 

separators,  50 
washers,  50,  5 1 

Central  R.  R.  of  Georgia,  i,  27,  33,  6r 
Charleston,  Cincinnati  &  Chicago  R.  R.,  118-121,  27 

36 

Charleston  &  Savannah  Ry.,  54,  83 
Chicago,  Burlington  &  Quincy  R.  R.,  34 
Chicago,  Milwaukee  &  St.  Paul  R.  R.,  i,  37,  84 
Chicago  &  Northwestern  R.  R.,  31,  32,  35,  96 
Chicago,  Rock  Island  &  Pacific  R.  R.,  30 
Chicago  &  West  Michigan  R.  R.,  33,  92,  102 
Chisel,  59 
Cincinnati,  New  Orleans  &  Texas  Pacific  R.  R.,  33, 

61 

Cincinnati  Southern  Ry.,  61 
Classification,  general,  5 
Clearing,  61 

Cleveland,  Akron  &  Columbus  Ry.,  61 
Cluster-bent  trestles,  42 
Combustible  matter,  55 
Compound  timber  trestles,  40 
Construction  records.  72 
Corbels,  31 
Cost,  annual,  2 
Cost  of  embankment,  3 
Cost  to  height,  5 
Cost  of  trestles,  5 
Counter-posts,  39 
Countersunk  bolts,  49 
Cram's  pile-hammer,  19-23 
Creosoted  trestles,  64 
Crib  foundations,  26 
Cross-cut  saw,  58 
Curves,  trestles  on,  42,  63 
Cut  spikes,  45 
Cutting  off  piles,  11,  12 
Damages,  66 
Defective  work,  66 

Delaware  &  Hudson  Canal  Co..  30,  31 
Delays,  66 

Denver,  &  Rio  Grande  R.  R..  I,  86 
Denver,  Texas  &  Fort  Worth  R.  R.,  33 

157 


'58 


INDEX. 


Design,  5 

Dimensions,  62 

of  stringers,  34 

Distribution  of  trc-stles,  2 

Division  estimate,  75 

Double-track  trestles,  43 

Dowels,  48 

Dowel-joints,  30 

Drawings,  62 

Drift-bolts,  46,  47,  48 

Drift-bolt  joints,  30 

Drip-holes,  27 

Drivers,  pile,  13 

Driving  piles,  9 

"  "   ,  method  of,  13 

Dry  stone  foundations,  27 

Durability  of  piles,  6 

Economy  of  trestles,  4 

Elevating  rails,  42,  43 

Embankment,  3 

,  connection  with,  52 
"  ,  cost  of,  4 

Ends  of  guard-rails,  37 

Engineer,  67 

Engineering,  field,  56 

Erecting,  57 

Esquimalt  &  Nanaimo  Ry.,  154 

Estimate,  75 

Expenditures,  annual,  2 

Extra  work,  66 

Fastening  floors,  38 

stringers,  34 

Field-engineering,  56 

Fire-protection,  5,  54,  65 

Floor-fastening,  38 

Floor-systems,  35,  36 

Floors,  solid,  43 

Florence  R.  R.,  61 

Framed  bents,  24 
"       trestles,  5 

Framing,  63 

French  Broad  Valley  R.  R.,  61 

Foot-walks,  54 

Force  accounts,  67 

Fort  Worth  &  Denver  City  Ry.,  128 

Foundations,  classification,  24 
,  crib,  26 
,  dry  stone,  27 
,  grillage,  25,  26 
,  masonry,  24 
,  mud-sill,  25 
,  pile,  24,  25 
,  solid  rock,  26,  27 
,  sub-sill,  25 

Georgia  Pacific  Ry.,  33,  61,  124 

Grillage  foundations,  25,  26 

Grip,  49 

Guard-rails,  35 

,  ends,  37 


Guard-rails,  inside,  37 
, joints,  37 
Guards,  rerailing,  53 
Gulf,  Colorado  &  Santa  Fe  R.  R.,  33,  61 
Hammer,  58 
Hammer,  pile-driver,  9 
Hand-car  refuge-bay,  54 
Hand-saw,  58 
Hatchet,  59 
Height  of  bent,  30 
High  trestles,  classification,  40 
Highways,  65 
Hoisting-machines,  60 
Holes,  drip,  27 
Information,  67 
Inside  guard-rails,  37 
Inspection,  4,  65,  77,  78 

"         ,  Burlington,    Cedar    Rapids   &    Northern 
R.  R.,  82 
Inspection  Erie  Ry.,8o 

Plant  System,  80 
records,  79 
Intercolonial  Ry.,  150 
Iron,  specifications  for  wrought-,  64 

"    cast-,  65 

Iron,  weight  of  bar,  48 
Item  sheet,  74,  75 
Jack-stringer,  34 
Joint-plate,  30 
Joints,  29 

"     ,  dowel,  30 
"     ,  drift-bolt,  30 
"     ,  guard-rail,  37 
"     ,  plaster,  30 
"     ,  preservation  of,  61,  63 
"     ,  stringer,  33 

Kansas  City,  Fort  Scott  &  Memphis  R.  R.,  36 
Kewaunee,  Green  Bay  &  Western  R.  R.,  140 
Knee-braced  trestles,  43 
Labor,  65 
Lag-screws,  49 
Lateral  bracing,  40 
Length  batter-posts,  28 
Life,  2,  4 

Liquors,  intoxicating,  66 
Literature,  4 
Log- hook,  60 
Log-wheels,  60 
Longitudinal  bracing,  39 

Louisville  &  Nashville  R.  R.,  i,  31,  36,  43,  98,112 
Maintenance,  2 
Mallet,  58 

Masonry  foundations,  24,  73 
Material,  65,  70 
Mathematics,  5 
Matter,  combustible,  55 
Maul,  spike,  58 

Milwaukee  &  Northern  R.  R.,  140 
Minneapolis  &  St.  Louis  Ry.,  94,  122 


INDEX. 


Missouri,  Kansas  &  Texas  Ry.,  36 

Missouri  Pacific  R.  R.,  i,  15 

Mud-sill,  25 

Nails,  45 

New  Orleans  &  Northeastern  R.  R.,  61 

New  York  Central  R.  R.,  i 

New  York,  Lake  Erie  &  Western  R.  R.,  i,  30,  31,  80 

New  York,  New  Haven  &  Hartford  R.  R.,  25 

New  York,  Ontario  &  Western  R.  R.,  24 

New  York,  Providence  &  Boston  R.  R.,  33,  148 

New  York,  West  Shore  &  Buffalo  R.  R.,  36,  37 

New  York,  Woodhaven  &  Rockaway  R.  R.,  31,  146 

Norfolk  &  Western  R.  R.,  1 1,  26,  42,  43,  72,  108- 1 1 1 

Northern  Pacific  R.  R.,9,  10 

Notching,  30 

Numbers,  bridge,  83 

Nut-locks,  51 

Ohio  Connecting  Ry.,  31,  61,  116 

Oregon  &  Washington  Territory  R.  R.,  126 

Oregon  Pacific  R.  R.,  33,  114 

Packing  blocks,  32 

"       washers,  50 
Payment,  68 
Peavey,  60 

Pennsylvania  R.  R.,  33,  34,  36,  37,  39,  104 
Pile,  batter,  7 

"     bents,  6 

"     caps,  12 

"     drivers,  13 

"     ,  car,  15-19 
"     ,  scow,  13-15 
"     ,  simple,  13 

"     driving,  9,  10 

"          "        methods,  13 
"        record,  10 

"     foundations,  24,  25 

"     hammer,  steam,  19-23 
Pile-point,  8 

"    ring,  9 

"    shoes,  8,  9 

"    trestles,  5 
Piles,  62 

"    ,  cutting  off,  1 1,  12 

"    ,  durability,  6 

"    ,  length,  9 

"    ,  size,  6 

"    ,  spacing,  6,  7 

"    ,  specifications,  6 

"    ,  splicing,  8 

"    ,  test,  9,  10 
Plaster-joint.  30 
Plate-joint,  30 
Plumb-posts,  28 
Point,  pile,  8 

Pontiac,  Oxford  &  Port  Austria  R.  R.,  35 
Posts,  28 

"   ,  batter,  28 
"    ,  counter,  39 
"    ,  plumb,  28 


Poughkeepsie  Bridge,  8 

Premium,  83 

Preservation  of  joints,  61,  63 

Price,  68 

Prices  of  trestle-material,  u 

Proposal,  68 

Protection  against  fire,  54 

Quantities,  67 

Queen  &  Crescent  System,  i 

Rails,  elevating,  42,  43 

"    ,  guard,  35 

"     ,  inside  guard,  37 
Rate  of  pile-driving,  10 

"  trestling,  i 
Records,  construction,  72 
Refuge-bay,  54 
Relative  cost,  4 
Repair,  4 

Repairs,  annual  cost,  2 
Replaceable  trestle,  2,  3 
Report,  track-walker's,  77 
Rerailing,  5 

guards,  53 

Richmond  &  Danville  R.  R.,  37,  130 
Ring,  pile,  9 
Risks,  65 
Roads,  65 

Round-timber  trestles,  43 
Rules,  59 

St.  Louis  &  San  Francisco  R.  R.,  i 
St.  Paul,   Minneapolis  &  Manitoba  R.  R.,  33,  36,  61, 

142-145 

San  Francisco  &  North  Pacific  R.  R.,  33,  35,  106 
Savannah,  Florida  &  Western  R.  R.,  30,  54 
Saw-mill,  60 
Saws,  58 

Scow  pile-driver,  13-15 
Screws,  lag,  49 
Separators,  32,  50 
Shenandoah  Valley  R.  R.,  31 
Ship-augers,  59 
Shoes,  8,  9 
Sills,  27 

"   ,  bank,  52 

Solid  rock  foundations,  26,  27 
Spacing  bents,  30 
"        piles,  6,  7 
Specifications,  standard,  61 
Spike-maul,  58 
Spikes,  boat,  45,  46 

"      ,  cut,  45 
Splicing  piles,  8 
Split  caps,  u,  30 
Square,  59 
Staking  out,  56 
Standard  design,  5 

"  specifications,  61 
Steam  pile-hammer,  19-23 
Stone  foundations,  27 


i6o 


INDEX. 


Stringer-joints,  33 
Stringers,  32 

"       ,  dimensions,  34 
,  fastening,  34 
,  jack,  34 

"       ,  Pennsylvania  R.  R.,  34 

"       ,  trussing,  35 
Sub-sill  foundation,  25 
Sway-bracing,  39 
Technical  terms,  ix 
Template,  batter-post,  29 
Tenon,  12,  29 
Terms,  ix 
Test-piles,  9 
Test-pile  record,  10 
Texas  &  Pacific  Ry.,  36,  51 
Thimbles,  50 
Ties,  35 
Timber,  measurement,  71 

,  quality,  62 

Toledo  &  Ohio  Central  R.  R.,  40 
Toledo,  St.  Louis  &  Kansas  City  R.  R.,  36,  37,88,  137 
Tools,  29,  58 

"       for  repair,  83 
Track-walker's  report,  77 
Trains,  65 
Trenail,  12 
Trespass,  66 
Trestle  material,  n 
Trestles,  classification,  40 

"     ,  cluster-bent,  41 

"    ,  compound  timber,  40 

"     ,  cost,  4 

"     ,  creosoted,  64 

"     ,  curved,  42,  63 


Trestles,  distribution,  2 

"     ,  double-track,  43 

"     ,  economy,  4 

"     ,  framed,  5 

"     ,  knee-braced,  43 

"     .  pile,  5 

"     ,  replaceable,  23 

"     ,  round  timber.  43 

"     ,  solid  floor,  43 

"     vs.  iron  bridges,  4 

"     vs.  embankment,  4 
Trestling,  amount,  i 
Trussing  stringers,  35 
Union  Pacific  R.  R.,  i 
Values,  capitalized,  2,  3 
Vancouver,  Klickitat  &  Yakima  R.  R.,  u 
Vicksburg  &  Meridian  R.  R.,  61 
Vicksburg,  Shreveport  &  Pacific  R.  R,,  61 
Wabash  R.  R.,  i 
Walks,  foot-,  54 
Washers,  cast-iron,  50,  51 

"       ,  packing,  50 

"       ,  wrought-iron,  50,  51 
Weight  of  bar-iron,  48 
"        "  bolts,  49 
"        "  drift-bolts,  46 
Wheels,  log,  60 
Wisconsin  Central  R.  R.,  33 
Wrenches,  60 
Wrought-iron,  specifications,  64 

"     washers,  50,  51 
Work,,  defective,  66 

"     ,  extra,  66 
'   "    ,  preservation  of,  67 


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